What RPM range do I accelerate and shift for best fuel economy?
 

Hello all!


This is my first post here and I'm happy to say that I found this website.

I've been researching online for hypermiling tips and while most are straightforward, others are more complex.

The one that I need the most help understanding and putting into practice is:
How should I accelerate??? Meaning at what speed, time and intensity.
I've read many findings that some receive better mileage while accelerating slowly while others find that accelerating more quickly yet smoothly yield better results.

*NOTE: If anyone could tell me how to shift efficiently that is specific to
this vehicle's layout, then that would be even better.*

Here are the estimated shift points that I have witnessed in my 5 years of ownership:

1st Gear: 17 MPH
2nd Gear: 27 MPH
3rd Gear: 37 MPH
4th Gear: 47 MPH

-At what RPM should I accelerate before allowing the automatic transmission to shift?

- What Engine Load should I use whilst accelerating?: this term CONFUSES me! (Example: 70% load)
Gauges aside, how does one measure how much load to use while accelerating
for the best fuel economy just with the feel of your foot on the pedal?


If I am missing something here, please do not hesitate to let me know :)







I have a 2001 Toyota Camry LE.
Here are the specs:

2.2L 16 valve DOHC I-4 cylinder
4 speed automatic transmission w/OD
.3 drag coefficient
3,100 curb weight
136 HP @ 5200 RPM
150 lb.-ft. @ 4400 RPM
18.5 gallon tank
Cruise control
DFCO @ 1400 RPM

RECENT UPGRADES:
New WIX air filter
New 15 inch Michelin Primacy tires
Oil changes every 4,000 miles

There is a spreadsheet often called a map that the engine management uses that has load listed as one of the variables. With my old Subaru it had engine RPM starting at upper left and going down to the max toward the bottom. Then going across the top starting at the top left going toward the right was columns called load like an excel spreadsheet. For example, if you were idling at 850 rpm it would highlight a cell across from 850 rpm in the column that had say zero or 10% load. If I were climbing a steep hill at 850 rpm with the gas pedal all the way to the floor it would highlight a cell across from 850 rpm in the 100% load column. The software uses the highlighted cell that dances around the spreadsheet to manage the engine parameters. As you can image it would use less fuel at idle in the zero column as opposed to the 100% load column where it will need to add as much fuel as it can use for the amount of air available in the cylinder. Load is much like how hard you'd be straining to do a job. I hope that helps.

Where do I find the map for my specific car?

My torque peak is 150 lb. ft. @ 4,400 RPM.

So 70-75% of 4,400 RPM would mean that I should accelerate around 3,000 RPMs? That seems a bit high to me, but then I could be wrong.

Since my Festiva "L" doesn't come with a tach, I'd have to purchase one to know the rpms, but there's no way I'm shifting over 2K rpm ever.

I shift at:

1st - 7 mph
2nd - 15 mph
3rd - 24 mph
4th - 33 mph

I bump start at:

greater than 5 mph - 5th gear, halfway out on clutch to start it, then quickly switch into appropriate gear

less than 5 mph - key start in neutral

In my SUV I have a mpg gauge. When I'm climbing a hill or accelerating it may read 8 mpg (heavy "load" or strain). When I'm on a smooth flat road maintaining my speed I may see 60 mpg (light "load"). I may be running 3000 rpm but the engine is not working very hard so its not using very much fuel. My car is geared to spin pretty fast on the highway. I don't have a choice to change my RPM if I want to maintain my speed, but I can request more fuel with the gas pedal. It may not go any faster but it will make more noise. Its under more of a load. It takes practice to find the best spot for your vehicle. It's kind of like riding a 10 speed and finding the right gear to keep your legs from burning. Sometimes pedaling faster makes it easier sometimes not.

My car must have taller gearing because when I'm driving 55 MPH, it's right at 2,000 RPMs.

Hills are my biggest challenge because I still have not mastered the hypermiling techniques for them yet.

I usually try to keep my shifts at 1,800-2,200 RPMS but I may be doing it incorrectly, I'm not sure. I just like to baby my car.

With that low of shift rpm, your probably accelerating for a long time, by dragging it out, you are staying in 1st and 2nd a long time where mpg are terrible, accelerate faster to get into D/OD and lock up the torque convertor.

With my Stratus with a 2.4 3,000 rpm worked well, 1/2-3/4 throttle to 3,000 rpm, left off to get it to shift, back on as hard as I could without making it to down shift. With my auto tranny it is real hard to get 70% load after 1st gear because it will down shift. So thinking about % load has no value.

Shift light on my Cobalt is at 2k, but it's a manual, so I can load the engine for greater efficiency, but sometime like accelerating up hill, it think it's better to get to 55 in 3rd and then jump to 5th than take 2x long to get to 55 if I shifted by the light. 55 rpm = 2k.

Best mpg gains are really on the other end of the road when you need to stop, a good coast = better mpg and brakes last longer.

I usually accelerate like a granny, it probably takes me 10-15 seconds to get from 0 to 45 MPH on flat to slightly elevated terrain.

I've been averaging about 30 MPG using this method, however I want to increase that number.

How do I know how much throttle I am using??

You have to guess at the load unless you have a device that can access your cars software through the OBD port. Also, throttles are not linear. You may be only breathing on the go pedal but the software may be programmed to give 50% instead. Chryslers I've driven lately want to get after it pretty hard even if your trying to be gentle on take off. With an automatic your going to have frictional loses from the torque converter. I've been told that there may be as much as 20% loss on my 87 Dodge pickup under heavy load. I have rigged an overdrive switch so I can get lockup very early to avoid a lot of that loss. It will only lock in 3rd gear so I have to deal with the losses until I get to that gear and then I may be lugging the engine too much to get the most mileage from it. I can only manage 13mpg in that vehicle. My wifes auto gets 31-35mpg and its a conventional three speed automatic that with lockup in between every gear to get six effective speeds. Thirty mpg is about what I've seen in Camry's like yours. I think if you have an automatic 4 cylinder its better to get briskly going at first and get to torque lockup maybe around 30mph? I seem to remember that 2200rpm being good point for 2 liter 4 cylinders in general.

From all the testing I've seen, acceleration technique really doesn't matter that much. Its much more important to avoid brake use, keep your speed down on the highway, etc.

I generally accelerate at a moderate rate. I try to load the engine to ~80%. RPM doesn't matter much unless you're redlining every shift. If you want to go accelerate a bit faster, go for it. Typically, I shift most cars around 2500.

You should be able to achieve a fair bit better than 30 mpg in that Corolla.
Learn more about DFCO and when your car is in/out of dfco. You can run along the back roads slowly getting up to 55 mph and coasting (in gear) back down to 45 then repeat the cycle over and over. Watch your mpg jump.

I drive almost exclusively stick shift cars so my automatic transmission advice is more limited to the dfco testing I have done than when to upshift on acceleration. I do however believe that accelerating too slowly will reduce, not increase, your economy. Get up into the highest gear at a reasonable pace and then do your cruising as slow (traffic allowing) as you can in the tallest gear without lugging the engine. I'd guess a good engine rpm for that 1.8L would be 17-18 hundred rpm. Hopefully that will keep you in the 45-50 mph range. Back roads (as opposed to the expressway) are really your friend for economy.

Welcome to the nut house. Strength in numbers!

EDIT: oops, my bad. I thought I read Corolla. The Camry is a fair bit heavier and the 2.2 will be a tad thirstier than the corollas 1.8. 30mpg isn't too bad but with information and the formation of new habits you will see an increase. Good luck.

Just easy into it smooth and keep pushing till target rpm but you don't need to floor it or it may go into fuel enrichment. I doubt you make it to half throttle. You want to get out of first quick, but not by leaving a trail of rubber.

Pick a new target rpm say 2500 so not that big of change. Try that for a tank, next tank try 3000. As SGII or other instrumentation helps a lot here as it doesn't take as long to get feed back.

You won't be able to use too much throttle after first gear because it will cause a downshift. Right up to that point is the right amount (IMO).

I'm not exactly sure when my car reaches torque lockup but I do know I reach 4th gear/OD around 47 MPH. I should probably use a stopwatch to record my acceleration rates and keep a record.

I completely agree! I'm no speed demon, I like to be safe as well as efficient, though I do wish trucks could get the same mileage as cars :)

I think that's what my problem has been was taking my time getting up to speed, after reading many different sites suggesting that slower is better but I guess they failed to mention not in this case.


My car is at 1,800 RPM at 50 MPH, 2,000 RPM at 55 MPH, and so on...



Haha, it's perfectly alright! The Corolla is just a "mini" Camry, so don't feel bad! ;)

That sounds like a good experiment to try.
I ordered an Ultragauge because it's priced lower than the ScanGauge II.


The only thing I'm not looking forward to is calibrating it, according to the manual, it looks like a pain!

You just need to get a scangauge or other obd2 software find a road from 0-55 like a left turn onto the highway. And test it. I have found in my KIA most efficient is holding the thottle to TPS 25 and that's about half throttle. Shifting from 1> 3> 5 slowly going.

In my girlfriends 6 speed auto 2.5 I-5 2009 jetta its best to push it 3/4 of the way in getting to speed quickly and into 6th as soon as possible.

I would think most if not all automatic transmission cars are better off going slowly from a dead stop until 5MPH and then using 3/4 throttle.

I also think the manual transmission can accelerate more efficient ly. The difference in my KIA accelerating slowly and smooth vs quick heavy throttle and shifting at 2k rpms is nothing I have seen a difference at 1-4 mpg and during accelerating. Now in the jetta it is a much larger 4-8 mpg from a dead stop to 55 or 65 mph

Basically without getting too technical, accelerate at the highest throttle opening possible without delaying your upshift points.

regards
Mech

For me calibrating MPG was easier with the Ultragauge as you can fine tune it on the fly to an exact percentage. (21.4% for me) Can only calibrate the Scan Gauge when filling up & can't fine tune the MPG percentage offset as precisely.

Unfortunately setting up most everything else with the Ultragauge is a lot more tedious than the Scangauge, but worth it once dialed in.

I hate to ask this and this might sound like I'm totally helpless but would you mind giving a step by step process of complete calibration of the Ultragauge?

The online manual is a bit overwhelming. The steps are all over the place and not very clear.

I took a drive last night and accelerated up to 2500-3000 RPMs after every stop. I got up to 4th gear much more quickly than I did using the slower method, but at the end of the drive, my gas gauge needle dropped from half to almost a third.

Is this normal? Can the gas needle really be trusted or am I doing something wrong? :confused:

I usually use cruise control on the highway consistently because I can't keep a steady speed with my foot alone.

**NOTE: There are some slight elevations around my area as the ground slants lower going closer to the rivers I have to cross due to natural draining and erosion over the years.

The odometer(miles)needs to be calibrated first. Do you have a GPS? Have you ever checked to see if the OEM odometer is fairly accurate?

The closest thing to GPS I have is the Maps app on my iPhone powered by TomTom. It creates routes and pinpoints my location.

My house is exactly 1 mile from the main stretch and my odometer has always shown exactly 1 mile.

I suggest 100 miles as a benchmark for better accuracy. My ododmeter is off 2.1 miles every 100 miles using GPS. You can use mile markers on major highways as well.

Wow, 100 miles? I don't think I have time to take a road trip that long.



Does the terrain of the road matter?

Terrain shouldn't matter. I discovered the ododmeter discrepancy while driving through Skyline Drive in Virginia. Thought the mile markers were off, but verified the result on an interstate hwy with the same outcome.

Does it have to be 100 miles?

No, just makes it easier to record miles traveled w/o instrumention when calculating MPG. 25-50 miles should work too, but the more the better.

Ok I tried accelerating around 2500-3000 RPM from every stop. While I got up to top gear much more quickly, my gas gauge dropped much more than usual.

So maybe this technique does not work for my car OR I am doing something incorrectly.


HELP?! :/

I talked with a state road worker who put in the mile markers on the highway to find out how it was done. He said he got in his work truck and every mile by his odometer they got out and put up a sign.

Probably better to use your GPS for actual mileage and speed.

I'm still experimenting too. I don't notice any more enrichment even if I accelerate to 3500 rpm. I've been revving to that in the first two gears and skipping to 6th. With this vehicle it takes everything its got, loaded and A/C to accelerate fast enough to enter traffic without getting run over so sometimes I have to get into 3rd pretty hard too. I do notice a huge difference in reported mileage as I go through the gears. Its something like 1st(8mpg), 2nd(11mpg),3rd(18),4th(23) and from then on I'm drastically reducing load. I still see 20-24mpg in 6th climing moderate hills I guestimate 60-70% load but I'm not pushing the pedal down very far (maybe quarter of the way). One one downhill spot from a stop sign I go through the gears without getting above 1500 rpmand almost no load because I can take my time and let it build speed from gravity too without having to worry about traffic running me over.Mileage doesn't look much better than above until I get 5th or 6th gear.

I DID IT!

I drove 504 miles this past trip cycle in mixed traffic and averaged 37.4 MPG!!!

This is the most I've ever earned and I'm very proud of myself! :D

Excuse my excitement, I'll calm down lol. I just can't believe how well I did in such a big car as the Camry. WOOHOO! My biggest changes were implementing DWL and not using air conditioning. I've listed my fuel up in my garage along with what I did differently from my last trip cycle.

My new goal is to reach 40 MPG average ;)

Wow! Man, you nailed it! I'd be excited too. That's killer mileage:thumbup:

Thanks, brother! I'm more motivated than ever now! ;)

It annoys me that whether I accelerate at low RPMs or high RPMs, my fuel economy stays low regardless until I get into Overdrive.

I also hate accelerating uphills. Gravity is no help there. I wish there was some way to minimize the decline in fuel economy.