Hypermiling Techniques

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Ecomodder has an impressive list of hypermiling tips. This is the main wiki page for the list and links to details about these tips.

All hypermilers are encouraged to modify the pages contained in these links with their own experiences. For all tips please only list scientifically backed information and please provide references where appropriate. Efficiency improvement results should only be based on back to back tests with the same conditions. If there is no proven tested efficiency improvement listed, hypermilers are welcome to list an estimated efficiency improvement however please state that it is an estimate.

Any theoretical and untested tips please only include in the unproven mod section below.

As this is a wiki please note anything you place into the wiki can be overwritten or deleted by other users.

For any significant change suggestions to this page please discuss on the forum linked below

Main Hypermiling Tip Page Forum Discussion Link

Drivers can also perform modifications to their cars for higher efficiency gains. See below for a wiki with a comprehensive list.

Car Efficiency Modifications Wiki

Contents

Getting started

Modification Efficiency Improvement Notes More Information and How To
Drive less miles not driven is a popular way to measure this a) Live closer to work;

b) carpool;

c) bicycle;

d) walk;

e) take public transit

Attend a driving clinic Need user data
Reduce car weight Need user data the additional weight you carry in your vehicle doesn't ride for free. It takes energy to move it around. Weight_reduction
Let the most efficient driver drive Need user data More than one licensed driver in the vehicle? Let the most efficient driver drive! And take the opportunity to learn from his/her wisdom.
Join a fuel economy forum 10.6% (one user) Join an outstanding forum to learn ways to increase your fuel economy by talking to others who share your enthusiasm and goals. Join EcoModder

[1]

Remove unused roof racks 14.6% Single user If your vehicle come with a roof rack and you don't use it, remove it. Same holds true for bike racks. Doing so will reduce aerodynamic drag, resulting in better fuel economy. Aerodynamic mods: Removing roof rack
Check tire inflation regularly Need user data Make sure that your tire pressures are, at minimum, set to manufacturer specifications. the higher the pressure, the less rolling resistance. Tire pressure more info
Track your fuel consumption None by its self, can be used to modify driving One of the first steps in improving efficiency is tracking fuel consumption. While tank to tank feedback isn't ideal for feedback on driving technique, recording and minoring your "big picture" can be great motivation. EcoDriving 101 – Tracking Fuel Consumption
Use a fuel consumption display 27.8% average based on 2 users Feedback is absolutely critical to improving driving habits. Most popular: ScanGauge

DIY: MPGuino and others

Route selection and trip timing

Modification Efficiency Improvement Notes More Information and How To
Take the road less traveled will all more driving change Generally speaking, if you have the option of choosing lightly traveled roads over busier ones, you give yourself more flexibility to employ a wider range of fuel saving techniques than if you are surrounded by other vehicles.
Leave early and don't rush will all more driving change the enemy of efficient driving is finding yourself in a rush. Leave for your destination a little early so you don't feel pressure to drive faster, brake later and otherwise fall back into bad habits.
Crosswind barrier I know it helps me but we need more user data Headwinds aren't the only winds that increase fuel consumption - cross winds can have a large negative effect as well. In crosswind conditions, choosing a route with a barrier (trees or buildings) along the edge will save fuel compared to a road in the open. Crosswind barrier details
the 'corridor effect' Need user data All else being equal, traveling at a constant speed on a freeway within a flow of traffic (in the same direction) is more efficient than going the same speed in isolation. the reason is aerodynamic: a flow of traffic generates a localized wind current in the direction of travel. You will benefit from this artificial breeze.
Note your transition points Need user data If you regularly travel the same roads, make a conscious effort to note (memorize) the points along the way where transitions occur that maximize efficiency. EG. memorize where you can initiate a coast to just make it to the next stop sign. Or note at what speed you can crest a hill so you're traveling just fast enough for the next transition after the descent.
Time your gas station trips Need user data Plan to refuel your car during off-peak times to avoid lines and excessive idling.
Avoid drive-thrus Need user data Avoid drive thru windows. They lead to excessive idling.
Lane of least resistance Need user data In multi-lane traffic, choose the "lane of least resistance" to avoid unnecessary and unpredictable braking/changes in speed. EG. avoid lanes where buses are starting and stopping, or cars may be braking unpredictably to turn into driveways/parking lot entrances.
Avoid stops at bottom of hills Need user data Avoid roads with stops at the bottom of hills (which force you to brake and waste the kinetic energy you just gained going downhill).
Take advantage of the wind Need user data If possible, time trips to take advantage of strong tailwinds. Avoid setting out into strong headwinds/crosswinds.
Choose smooth road surfaces Need user data Choose a route with a smooth, paved/concrete surface over gravel or rough, broken roads, all else being equal. Smoother surfaces offer reduced rolling resistance.
Avoid bad weather Need user data Avoid driving in inclement weather if possible, as rain/snow/slush can dramatically increase rolling resistance. the exception to this rule may be when high winds (tailwinds) can be used to your advantage.
Avoid peak traffic Need user data If you have the option, avoid travel during peak traffic times. With the roads full of other drivers, you have fewer options for using driving techniques that the herd doesn't typically use or tolerate (e.g. reduced highway speeds, drawn out coasting up to stop signs, etc).
Drive when it's warm out Need user data If you have the flexibility, time your trips to coincide with warm temperatures (ie. middle of the day) rather than cold (night/early morning). Cold tires and drive train experience more rolling and mechanical resistance, and a cold engine is less efficient.
Pick up cargo "high", deliver "low" Need user data If possible, shop at stores that are higher in elevation than your home. That way the extra weight you pick up (shopping items) is on board for the descending return leg where it's less of a penalty than it would be on an ascending return leg.

Sub/urban driving

Modification Efficiency Improvement Notes More Information and How To
Conserve momentum: stop sign 'stop and crawl' Need user data When multiple vehicles ahead of you are progressing through a stop sign (or a right turn at a red light), this represents a mini 'stop and crawl' situation normally found in a bumper to bumper traffic jam. Time your approach, to arrive at the stop sign as the last car ahead is departing.
Conserve momentum: take a shortcut Need user data Sometimes options exist to go through corner parking lots, side streets, or alleyways to get around having to come to a stop at an intersection or behind another vehicle. Of course the utmost care must be taken in parking lots as they present their own risks (pedestrians, vehicles reversing from parking spots, etc.) Also, cutting through corner parking lots may be illegal in some areas.
Combining errands: do the longest leg first Need user data When combining multiple trips into one journey, go to your farthest destination first, and work your way back. This ensures the vehicle is warmed up as much as possible before subjecting it to multiple starts and stops.
Minimize idling when stopped Need user data If you're going to be stopped for more than a few seconds, shift to neutral and shut off your engine. This is one of the main reasons hybrid vehicles get such good fuel economy in urban driving. Caveat 1: this assumes your vehicle is in good tune and will re-start immediately, every time. Caveat 2: if you're a defensive driver, you're habitually evaluating the risk of a rear crash when slowing and when stopped. Obviously you will want to leave your engine on in those circumstances (for a quick rear crash avoidance maneuver).
Traffic light timing - stale 'green', no pedestrian signal Need user data In the absence of any other indication about how stale the light is (eg. if there's no pedestrian signal or waiting cross traffic), assume that the green light ahead is about to change. Adjust your approach speed accordingly (IF traffic permits - ie. you don't hold anyone up) to avoid a full-on brake application should the light change.
Combine errands Need user data Avoid very short trips. If you have multiple stops, plan them to do all on the same trip. Fuel economy is enhanced once the engine is warmed up, so a longer "chain" of errands will result in better fuel economy than multiple short ones, particularly in cold weather.
Traffic light timing - red lights with sensors Need user data When approaching a red light, slow down early if there's a car in front of you that can trip the sensor so you may not have to come to a complete stop.
Traffic light timing - 'stale' green Need user data When approaching an intersection with a green light you can watch the pedestrian signal crossing light to help determine when it will turn yellow.

Highway Driving

Modification Efficiency Improvement Notes More Information and How To
Lights on for safety; lights off for MPG Need user data Depending on the vehicle, power demands of the ighting system ranges from a few watts to well over 100 watts, all of which is ultimately powered by gasoline. In the US, where DRL implementation is voluntary, automakers have an exemption from CAFE testing which permits vehicles' fuel economy to be tested with the lights switched off. Switching off DRLs where their safety contribution is minimal (eg. driving on a divided, controlled access highway) will save a small amount of fuel.
Find/adopt a 'blocker' for slower freeway speeds Need user data Some people are uncomfortable driving at speeds less than the average flow of traffic on multi-lane freeways. One solution is to find another vehicle going the speed you want to travel (large, conspicuous vehicles work particularly well) and drive either ahead of or behind it. (Note: this is not a suggestion to draft.)
Close the sunroof at higher speeds Need user data Some sunroof styles are better than others. the worst offenders are the kind which tilt and slide to the outside, on top of the roof. When open, these "roof-top spoilers" can significantly increase aerodynamic drag.
Drafting: cross wind Need user data In rare circumstances, it is possible to effectively "draft" a larger vehicle in cross wind conditions without following directly behind it. When cross wind conditions cause the low pressure area trailing the lead vehicle to extend into adjacent lanes, you can take advantage of reduced drag legally and with reduced risk. Note: 1) this is not describing side-by-side driving, but postioning that is offset to the rear. 2) While visibility directly ahead is increased, a significant chunk of the driving picture may still be blocked depending on the size of the lead vehicle.
Drafting: close behind (not recommended!) Mythbusters results from drafting a truck
100 ft: 10.9%
50 ft: 20.3%
20 ft: 26.5%
10ft: 39%
2 ft: 28.1%
1) At highway speeds there's no doubt that driving close behind a large vehicle dramatically reduces fuel consumption. 2) It's a stupid thing to do. It's not recommended for many reasons, not the least of which is that it's illegal in most areas, and doing so sacrifices the foundation of safe and defensive driving: your ability to see well ahead.
Windows Up Need user data Drive with windows up at higher speeds to minimize aerodynamic drag. Use flow-through ventilation if possible.
Reduce speed Need user data Aerodynamic drag increases exponentially with speed, so reduce highway cruising speed as much as practical and safe. Generally, a vehicle's most efficient speed is just after its highest gear has engaged.

MPG vs speed graph

EcoDriving 101 – Reducing Speed

Constant throttle position cruising Need user data Once up to speed, pick a throttle position and hold it. Advantages: more efficient than using the cruise control (which varies throttle position frequently and wastes fuel on hills). Disadvantages: less efficient than "driving with load" (DWL) / "target driving" (where the throttle is eased on inclines).
Cruise control - when to use it Need user data Set the cruise control if you're the type of driver whose speed creeps up higher and higher the longer you're on the road, or if you have difficulty holding a steady speed (it wanders up and down). But realize that cruise control is just a band aid for those behaviours. Generally it's less efficient than constant throttle driving, and much less efficient than "driving with load" / "target driving".
Cruise control - when not to use it Need user data Only use cruise control on flat roads. On hilly roads, cruise responds to changes in grade - by feeding in more throttle on the uphill and releasing on the descent - in the exact opposite way an efficient driver would.

Braking tips

Modification Efficiency Improvement Notes More Information and How To
the most efficient way to slow down Need user data When you *have* to slow down, here's an approximate heirarchy of methods, from best to worst. 1) coasting in neutral, engine off (ie. roll to a stop);

2) coasting in neutral, engine idling; 3) regenerative coasting (hybrid vehicles) 4) regenerative braking (hybrid vehicles) 5) coasting in "deceleration fuel cut-off" mode (in gear, above a certain engine RPM) 6) conventional friction braking (non-hybrid or hybrid) Choosing the right method depends on traffic conditions (following vehicles) and how quickly you need to stop.

Conserve momentum: avoid stopping Need user data Avoid coming to a complete stop whenever possible (and when safe and legal of course). It takes much less energy to accelerate a vehicle when it's already traveling just a few kilometers per hour than it does from a complete stop.
Hybrids: minimize regen braking Need user data While regenerative braking in hybrid vehicles - capturing braking energy into the battery - is more efficient than braking with conventional friction brakes, it's still not as efficient as 'driving without brakes' (DWB). So even if you drive a hybrid, you'll get better economy when you minimize use of the brake pedal.
"Drive without brakes" (DWB) Need user data Minimize use of the brake pedal. Each time you press it, you're effectively converting gasoline into brake dust and heat. Driving as if you have no brakes will cause you to do two things: 1) reduces 'excessive' acceleration, and, 2) extends the amount of time you spend coasting down to stops and turns. Obviously you have to balance use of this technique against traffic conditions so as not to adversely affect other drivers. EcoDriving 101 – Driving Without Brakes

Advanced techniques

Modification Efficiency Improvement Notes More Information and How To
Drive shoeless Need user data Some hardcore hypermilers drive in sock or bare feet so they can modulate the accelerator to the finest degree (particularly important when "driving with load" / "target MPG driving" at cruise.

It shouldn't be that surprising. Race car drivers typically wear extremely thin-sole boots for similar reasons: for the highest level of tactile feedback from the vehicle, and to better finesse the pedals.

Conserve momentum: brake hard Need user data It sounds like a contradiction, but there are rare times when braking hard can save fuel compared to coasting or light braking: it's a "damage control" technique when faced with an unpredictable/unanticipated stop or slow down ahead and not a lot of space.

An example: approaching a fresh red traffic light that had no other indicators to predict the change (no pedestrian signal and no cars waiting on the cross street). If you brake lightly/moderately, you will cover the entire distance to the intersection and have no option but coming to a full stop.

But if you brake quite hard initially, you can potentially scrub enough speed and buy enough time to coast the remaining distance to the intersection at a low speed. With judgment and some luck, you'll arrive at a fresh green light and avoid a full stop.

Obviously, rapid deceleration isn't a safe option if there is following traffic.

Make fuel economy a game/challenge Need user data Competing against yourself (or others) to get the best possible fuel economy can do wonders for increasing motivation to learn more, refine your skills, and try harder.

Several web sites like EcoModder.com permit you to track and compare your fuel economy against other drivers, and some organize informal fuel economy challenges.

Hybrid festivals (e.g. hybridfest.com, greengrandprix.com) periodically run fuel efficiency rallies where you can hone your skills in competition with others in real time.

Use the 'racing line' Need user data Knowing how to pick the "racing line" through a corner, when safe, can help to preserve momentum. Generally, the racing line is the path through a turn with the largest possible radius. It may permit a higher speed with more comfort (less body roll and g-forces), and less tire scrub.

Note this isn't advocating high speed turns, where the cost of increased tire wear may outstrip fuel savings. Even at low speeds, choosing the "racing line" has benefits.

Encourage a pass: the fake turn Need user data Drivers who travel below the normal flow of traffic should facilitate drivers approaching from behind to go past safely, with a minimum of interruption.

"Faking" a turn by signalling and moving into a turning lane (even though you intend to continue straight on) is one option.

Note: judgment and care is demanded so you don't mislead any driver into making an unwanted move as a result of your "miscommunication". You must be prepared to actually make the turn if your actions create a situation that would make it the safest option.

Encourage a pass: hug right Need user data Drivers who travel below the normal flow of traffic should facilitate drivers approaching from behind to go past, rather than force them to slow down.

One method of gaining the attention of the driver behind is to move your vehicle very obviously to the extreme right of the lane you're traveling in when it's safe for the following vehicle to pass.

Adding a turn signal to the move or the 4-way flashers may be even more effective.

Of course, pulling completely off the roadway onto the shoulder to let following traffic by is also worthwhile, if you have the option.

Hill tactic: don't waste potential energy Need user data When facing a red traffic light, or some other predictable stop/start situation at the bottom of a hill, you're better off stopping near the top before you've accelerated to full speed. Wait, and time your release to make it through on green, and you avoid turning your potential energy into brake dust and heat. (Also known as 'smart braking'.)
Engine off coasting 24% difference between engine off compared to idle coasting
Single user
Engine-off coasting (EOC) is one of the largest contributors to increased efficiency of hybrid vehicles, many of which automatically shut down the engine when the accelerator is released and the vehicle is coasting.

EOC can be accomplished in non-hybrids as well simply by shifting to neutral and switching the key from "Run" to "Acc" (being careful not to switch to "Off" and cause the steering to lock). As soon as the engine stops, return the key to the "Run" position or else you will be in danger of locking out your steering and crashing. Also be careful to not steer at all while the key is off to prevent a lock up.

This technique is best suited to cars with manual steering and manual transmissions. (Dramatically increased steering effort may be required in some cars with power assist. Also, most vehicles with automatic transmissions are not designed to travel with the engine shut off; the transmission may be damaged).

In non-hybrids, EOC is considered an advanced technique and should not be attempted until the skill developed away from traffic. In addition, coasting with the engine off is illegal in some areas.

the best way to EOC is with a kill switch that shuts off the engine without removing the key, thereby eliminating the dangers of locking the steering wheel.

Note: When the engine is off the brake vacuum reserve is not recharged by the engine therefore drivers with the engine off will only get a few brake presses before the brakes no longer work.

Quick Test: P&G with EOC vs w/o EOC shows 24% gain
Drive with load (DWL) Need user data AKA "target driving". Put most simply, this technique is accomplished by choosing a "target" rate of fuel consumption and ensuring you don't fall below it on hills (or in very strong winds, or any conditions which cause load to vary for a given speed).

In other words, you will back off the accelerator and lose speed (possibly also downshifting) as you climb, and gain that speed back on the descent.

It's far more efficient than pressing the accelerator more and more to maintain speed on the way up a hill and then releasing it down the other side.

DWL is how an efficiency minded person can greatly outperform cruise control in hilly terrain.

Obviously the ability to use this technique without adversely affecting other drivers depends on the traffic situation.

As well, fuel economy instrumentation is required to DWL/target drive to the maximum extent, though it can also be done using a vacuum gauge, and to a much lesser extent by the seat of the pants.

Heavy traffic: play the accordion Need user data If faced with worst-case "stop & crawl" traffic conditions, leave as much space ahead of you as possible and continually "accordion" that space to keep your vehicle moving near a constant speed while the cars in front of you stop & start.

Yes, some people will cut into the space you create ahead of you. Deal with it.

Note that this may aggravate following drivers who can't absorb the big picture, and that must be taken into account.

Pulse and glide (P&G) 30% improvement estimate Use pulse and glide (or "burn and coast") rather than maintaining a constant speed, where practical. Pulse and glide explained
Push it - 1 Need user data If you only have to move your car a very short distance - eg. out of the garage - consider rolling it rather than starting it up to move it.
Push it - 2 Need user data If you're starting out on an incline, give your car a shove to get it rolling as far as possible before starting the engine.


Parking (and departing)

Modification Efficiency Improvement Notes More Information and How To
Start up: wait for the opportunity to move Need user data Don't start the engine until there's actually an opportunity to start driving: eg. a gap in traffic when exiting a driveway or parking space.

You can plan even further ahead: don't turn the key until you know you can time the next traffic light down the street.

Parking tactics: orbit to bleed momentum Need user data If you find you have too much momentum after reaching your preferred parking spot, continue coasting further down the row or "orbiting" a spot until you can roll to a stop in position without touching the brakes.

(the extent to which you might continue 'orbiting' depends on whether your engine is on/off and whether you're driving a manual or automatic. Also, it depends on traffic in the lot, obviously.)

Parking tactics: gravity assist Need user data Slopes can be useful in manoeuvering into a parking place. One which I regularly back into (it can't be driven through) has a small slope across from it. I kill the engine approaching the slope, and engine-off coast backwards into the spot.

Gravity can be a hindrance in parking as well. Avoid driving down into a parking "hole" which you must drive out of later. Even if you EOC into the hole, you'll face a net efficiency loss when you drive your cold vehicle up and out later.

Parking tactics: avoid parallel parking Need user data For on-street parking, the better spot is one with enough room to pull in/out rather than multiple reverse/forward manoeuvering (parallel parking).
Parking tactics: reverse in Need user data If you have no pull-through spots to choose from, reverse in when arriving, instead of driving in when warm and backing out/turning around when the vehicle is cold and fuel economy is at its worst.

Also note that reversing into a flow of traffic is riskier (and therefore much slower and less efficient) because you may not have a clear view until your vehicle's back end is well out of the space.

Parking tactics: pick the periphery Need user data Choosing a spot in the "periphery" of a busy lot will be more efficient than navigating the rows of traffic/pedestrians to get as close as possible to the building or destination.
Parking tactics: pull-through spot Need user data Drive into a "pull through" spot, rather than a spot that requires reverse/forward manoeuvering.
Start up: not until you're adjusted Need user data Don't start the vehicle until you're settled in: seat, seatbelt & mirrors adjusted; passengers settled in as well.
Multiple vehicles: choose the one that's warmed up Need user data In a multi-vehicle household, if you have the choice of using similar vehicles, choose the one that was driven most recently if it's still warm.
Multiple vehicles: choose the most efficient one in the 'fleet' Need user data If you have a multi-vehicle household or workplace, choose the most efficient vehicle from the fleet that will accomplish the task at hand.
When changing direction, use brakes rather than engine Need user data When going from reverse to a forward gear (or vice versa), don't use the engine to stop the vehicle after the gear change, use the brake.

Transmission tips

Modification Efficiency Improvement Notes More Information and How To
Automatic transmission: key off, then Park Need user data Save a few drops of fuel by modifying your shutdown procedure: when parking, turn off the key *before* shifting to Park and setting the parking brake.
Manual transmission: cruise in high gear Need user data When cruising at a constant speed, shift to the highest gear you can use without lugging the engine.
Automatic transmission: highest gear/lowest RPM for posted speed Need user data When cruising, drive to the speed that allows the lowest RPM for the speed zone you are in.

EG. if the posted speed is 30 and your car shifts into 3rd at 35, you may be able to achieve the 3rd gear shift, then reduce and hold 30 without causing a downshift.

Automatic transmission: torque converter (TC) lockup Need user data Drive at the speed that allows the TC (torque converter) to lock up. This is often around 40-45 mph. Speeds just above this typically return the higest cruising fuel economy.
Automatic transmission: neutral when stopped Need user data Shift automatic transmissions to neutral when stopped (assuming you're going to leave the engine running). Remaining in drive wastes fuel as the engine continues to try to creep the car forward while being held back by the brakes.

Note: Some older cars which do not compensate the idle speed depending on engine load may use more fuel when in idle as the RPMs will go higher and therefore pump more fuel through the engine. Check your fuel usage meter to be sure.

Automatic transmission: upshift coaxing Need user data Some automatic transmissions can be coaxed to upshift sooner when accelerating by briefly releasing some throttle pressure, then re-applying to continue accelerating.
Automatic transmission: use OD (overdrive) Need user data If your transmission has an "OD" (overdrive) button or position, leave it engaged to ensure the transmission will shift into its highest gear as soon as possible.
Automatic transmission: use economy mode Need user data If your automatic transmission has a "power/economy" button, leave it in economy mode. This usually results in earlier upshifts and later downshifts, saving fuel.

Winter / foul weather

Modification Efficiency Improvement Notes More Information and How To
Wait for the snow plow Need user data Driving through fresh snow increases rolling resistance moderately to dramatically, depending on the depth/type of snow. Better fuel economy will result when you wait for the plows (or for other vehicles to pack the snow down) before setting out.

Similarly, getting stranded in a ditch or snow drift because you set out in bad weather is a surefire way to waste fuel if you need to idle the car to stay warm while waiting for help.

Winter: avoid wheel spin on ice/snow Need user data If you drive in ice/snow, avoid wheelspin when traction is low. Changing to dedicated snow/ice tires that offer better traction may save fuel.

Wheelspin is especially inefficient if your vehicle is equipped with brake assisted traction control.

Follow the leader in rain or snow Need user data In weather conditions that leave a lot of precipitation on the road - heavy rain or snow - drive in the tiretracks of the vehicle in front to reduce rolling resistance.

An exception to this tip may be on "rutted" surfaces where water tends to pool in the ruts. In that case, driving on the ridges between the ruts offers less resistance.

Winter: clean off snow & ice Need user data Completely clear snow & ice off your vehicle before driving. It will minimize your use of energy hungry accessories (defrosters), remove an aerodynamic penalty (increased frontal area), and reduce weight (a layer of ice and snow over an entire vehicle can weigh a surprising amount).
Winter parking: clean out the garage Need user data If you have one, clean out your garage so you can park your car inside during the cold months of the year. the faster warm up will return better fuel economy.
Winter: use heated parking Need user data If you've got the choice, heated parking will improve fuel economy. the potential downside is that it may increase the rate of corrosion if you drive where roads are salted.
Avoid heater use until the engine has reached operating temperature Need user data Engines runs rich until a minimum temperature threshold is reached. Running the heater blower before that has happened will slightly increase warm-up time and increase fuel consumption.
Avoid 'warm up' idling Need user data Don't idle your engine to warm it on a cold day. An idling engine gets zero miles per gallon.

Start to drive - under light loads - as soon as the engine is running smoothly (usually immediately). It's a more efficient way to warm the engine and entire drivetrain, including tires.

Hot weather

Modification Efficiency Improvement Notes More Information and How To
Cycle the A/C if you have to use it Need user data If you have to use the air conditioner, set the air flow to recirculate and manually turn the A/C on and off as needed. For greater efficiency, switch it on when under light engine loads or deceleration fuel cut off and off when under moderate/heavy loads. (Note: some newer vehicles do this automatically.)
Summer: park in the shade Need user data Parking in the shade will keep the inside of your vehicle cooler, which can help you minimize use of air conditioning.

If you must park in the sun, placing a sunshade in your windshield will keep your car significantly cooler.

Lightly colored interior Need user data Seats that are white or light tan absorb much less head than black or dark brown seats.
Use a beaded seat cover Need user data They work surprisingly well as an alternative to (or defer the use of) air conditioning, by letting air flow behind & beneath you. They keep you from sticking to your seat, and your clothes from sticking to you.

Other non-A/C options include ice vests and DIY ice water A/C units.

Minimize air conditioning use Need user data Air conditioning requires a lot of power. Use it sparingly.

Driving at city speeds, you'll save fuel by using your flow through vents and opening windows.

At highway speeds, whether A/C is more or less efficient than opening windows will depend on the speed, your vehicle's aerodynamics and A/C design.

Maximum legal tint Depends on many factors Have your front windows & windshield tinted to the maximum allowed in your state, and have the rear windows & rear windshield tinted as much as possible. Note: states can only regulate the tint amount on the front windows and windshield.
Trip timing: avoid the hottest times of day to reduce A/C use Need user data If you live where the weather is very hot, avoid driving if possible during the peak temperatures of the day when use of the air conditioner is "required."

Just generally good driving tips

Modification Efficiency Improvement Notes More Information and How To
Maintain a space cushion Need user data When driving on a multi-lane roadway, try to maintain a "space cushion" around you.

IE. avoid driving for any length of time beside a vehicle in the next lane. the more options you leave open for making a prompt lane change if one is needed, the afer and more efficient you'll be (if it means avoiding an unnecessary slowdown).

Maintain appropriate following distance Need user data Avoid driving so close behind another vehicle that you are forced to *immediately* brake if it begins slowing down. Important at all times, but particularly in sub/urban driving where traffic changes speed more often.

Leave enough space that you have time to choose other options (perhaps a lane change).

In addition, the greater your following distance, the better your forward visibility will be, which enables you to look well ahead and anticipate changes in the driving environment.

Be smooth Need user data Smooth use of the accelerator, steering, transmission and brakes is not only more comfortable for you and your passengers, it's also a little more efficient (less scrubbing of tires, energy lost through suspension movement). It's also better for the longevity of the vehicle and in general a sign of a skilled driver.
Use your horn defensively Need user data Defensive drivers will tap their horns to ensure they have the attention of other motorists or pedestrians in close quarters and potentially risky situations.

Being proactive will save fuel if it means you can avoid having to brake or stop unnecessarily.

Look well ahead & anticipate Need user data Your ability to drive efficiently depends on being able to anticipate changes in the driving environment. the way to do this is by constantly scanning well ahead in your intended path.

In city driving you should know what's happening at least 10-15 seconds ahead. On the freeway, at least 30 seconds visual lead time is appropriate.

Drive the posted speed Need user data Drive the posted speed limit or the minimum allowed, when safe to do so.

Miscellaneous

Modification Efficiency Improvement Notes More Information and How To
Don't keep up with the Joneses Need user data It easy to be competitive when driving. Resist knee-jerk retaliation to other drivers' aggressive actions. Don't let other drivers lead you astray from your driving style.
Minimize use of low range Need user data Many 4 wheel drive / AWD vehicles also come with high and low transmission ranges. Low range increases engine RPM and fuel consumption for a given gear/road speed combination compared to high.
Minimize use of 4 wheel drive Need user data the added friction of drive components in four wheel drive mode increases fuel consumption, especially when the center differential is locked and the vehicle is turning.
If you have to carry items outside the vehicle... Need user data Carry them on the back of the vehicle, instead of on the roof. Long, skinny items can even be carried beneath some vehicles (with ample ground clearance).

This is more important the faster and further you intend to go.

Minimize accessory loads Need user data Minimize use of electrical and mechanical accessory loads when safe and/or practical (lights, defrost, blower, electric heated seats, dvd players/screens, heated mirrors, etc).
Use a block heater Need user data Pre-warm your engine with an electric block heater. Engines are most efficient at full operating temperature, and the block heater helps it get there sooner. About 2 hours is the maximum time needed to pre-warm a small engine.
Drive like you ride a bike Need user data For you cyclists looking for a way to wrap your head around the subject of efficient motoring: drive like you bike.

Meaning, if you think about spending energy as wisely in your car as you do when you ride, you should automatically become aware of several of the major tips on this list, such as:

a) Ensuring your tires are properly inflated & vehicle is in good mechanical condition, for reduced rolling & mechanical resistance.

b) Smart braking: you'll spend more distance coasting up to stops (you don't pedal madly towards stop signs and then jam on the binders, do you?)

c) You'll "drive with load" on hills (you don't usually power up hills trying to maintain your previous cruising speed, do you?)

d) You'll reduce speed (because cyclists are highly attuned to the relationship between aerodynamic drag and the BIG DOG energy consumed to travel at high speed).

Avoid towing Need user data Trailer towing delivers the triple whammy of increased weight, higher aerodynamic drag, and a third (or fourth) set of tires for more rolling resistance.

Carry loads in the vehicle if possible.

If not, minimize towing speeds and adjust your technique to account for the extra momentum the trailer and its load will add.

Listen to slower music Need user data Leave the speed metal at home. Fast paced music can make a driver more impatient, more agressive and likely to speed. At the same time, slower paced music is more relaxing and tends to promote a more sensible driving style while also reducing stress.
Use E-Z Pass (or similar) if you commute on toll roads/bridges Need user data Especially handy for high-speed toll passes, because it avoids the slow down and acceleration back up to speed.

Generally useful anywhere it will help you avoid the stop-and-go/idling in lines approaching the toll booth.

Unproven Tips (Ideas or attempts)

Modification Efficiency Improvement Notes More Info Required

Dis-proven tips (Methods that dont work or hurt efficiency)

Modification Efficiency Improvement Notes More Info Required

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