Coasting in gear vs coasting in neutral-04 civic
 

Hey there, i'm new(er) to the whole hypermiling thing, although i have been tracking each tank of gas per fillup and average 39-42mpg per tank. (39 happens when i'm late and have to speed once in a while).

I shift around 2-2500 rpms (very low), have a very light/constant foot on the gas pedal, and generally drive like a grandmother.


I read the 100 tips for hypermiling, but i'm confused as whether it's better to coast/engine brake or to coast in neutral (i've tried coasting in neutral with the car off a few times but i'm wary of how i bump start it so generally i use the ignition, which could leave to premature starter wear so i don't do that often). My understanding is the injectors shut off a a certain rpm when in gear so it uses no fuel while coasting in gear, but i can't find what that rpm is anywhere (googled quite a few times!)

Sorry if this has been answered various times i just can't seem to find an answer, and i'm really looking to develop better hypermiling habits.

Anyways i have a 2004 civic lx 5 speed 1.7l, just a college guy trying to save some money.

thanks

It depends on the individual circumstance, although coasting in neutral is generally best if you have enough room to coast without braking.

Do you have any instrumentation to provide instant feedback? (Scangauge, Ultragauge, etc)

Bump starting is easy. Just slide it in gear and smoothly let off the clutch pedal, just like you do when you shift gears. When it catches, quickly push the pedal back in and it should be running. Then put it in the appropriate gear and let off the pedal again.

I only coast in gear if the hill is steep enough that I need brakes to maintain a safe speed. Otherwise it is neutral and typically engine off.

engine on coasting
 

My '99 civic used more gas during a trip using eoFc than expected. I suspected that the civic was using gas based on RPMs when the engine was off, and have not used eoFc since that time. Also I think bump starting is not as effective above 40 mph, where the range is on my trips.

Even if bump starting didn't [ lose momentum ] above 40 mph, there's not that much difference between having the engine on or off when coasting in neutral, plus the safety, electrical, efficiency and convenience benefits of having the engine on. Thus, I coast in neutral with the engine still on.

I'm confused... eoFc = Engine Off Coasting? How would the engine use any gas when off?

And how does bump starting "slow down the RPMs". Since you use momentum to start the stopped engine, bump starting, by definition, increases the RPMs (from 0 to 700ish for idle)

The engine is not generating power, but the car is moving and the electronics are still on.

There is another discussion of the same issue here.

A more accurate description would be uses momentum, i.e. slows down the car.

Search for DFCO. This subject has like 5000 threads already.

Annnnnndddd my 2cents is neutral engine off. Only use the engine when needed at a high load low RPM. That's seems to be the best way to travel. My engine is off unless my foot is on the gas.

The engine is still not using fuel.

That thread is about the Scangauge misreporting the engine behavior. When the engine is off, it is not using fuel because the computer knows the engine is not turning over (crank sensor reads nothing, cam sensor reads nothing, MAF reads nothing). If it were still spitting fuel out the injectors while coasting with the engine off, you would see some evidence of it such as severely rich running on startup and a dark cloud of smoke until it clears out.

I hope that ScanGuage can fix this glitch. It reads 0.02 gal / hour even when the engine is 0 RPM.

For my driving style Coasting in neutral typically yields more of an increase than engine off coasting. It's also less stress on the starter and alternator and battery.

I doubt the mileage dip from my engine off coasting was from anything but the alternator kicking in to compensate from the drain on the battery when the vehicle was off. My alternator typically sends out 14.5 volts and puts a noticeable strain on my engine. Driving at night with the ac on is death to my mileage

Once the alternator clicks into its maintain cycle the car runs noticeably smoother and a slightly higher rpm.

alright cool, i've been trying the engine off method but next tank (tomorrow) i'll start using neutral coasting and see what the results are

Most likely if you are using the starter to start the car it's using more energy than it is saving.

For bump starting I have always used third gear. If you ever have a dead battery or dead starter you must drop the clutch in third to get the vehicle running.

What I've always heard is that it takes more fuel to start the car than to let it idle, which was especially true in my camaro which puffs gasoline out of the tailpipe when it starts on a cold day. All of the emissions systems are removed but yeah.

So another stupid question but I drive a lot right around 30-35mph on the beggining and end of my commute, 5th tear isn't quiet bogging down but would it possibly be more efficient to use 4th at those speeds. I guess I'm trying to say how low is too low (rpm wise)

From an old wife perhaps? BMW and Ford claim the break even point is 3 and 5 seconds for their stop start systems.

Funnily enough, the starter and alternator have about the same rating on most cars, if you have an 80A starter, you'll have somewhere around an 80A alternator. This means if you run the starter for 2 seconds to start the engine, the alt should be able to replace that energy in 2 seconds (battery charge acceptance not withstanding).

True but we are still using wear items for minimal gains, @40 miles a gallon I doubt I would save $3 turning the engine on and off all the time at stop lights. Again referring to non bump start and engine off coasting. To me it's just added wear and tear on the vehicle, risking a $120 starter and a $120 battery for the sake of less than a gallon of gas per tank is not worth it.


I've driven a few start stop vehicles and was displeased with the experience and wished the cars had an option to disable the feature. Extremely bothersome when inching forward to see cross traffic to pull out into traffic. While nearly un noticeable for a majority of driving, trying to make a turn across an intersection was extremely un comfortable and un nerving

But again for my style I want a vehicle that maximizes efficiency without sacrificing comfort

If you use save one gallon of gas per tank, and use one tank a week, you'd have to be replacing the starter and battery once a year not to break even.

Bosch Stop/ Start is great on my Fiat, if I don't want it to switch off I just have to keep my foot on the clutch. There's also an over-ride button (as I'm pretty sure all systems do). Engine off at the lights (+ EOC) can half my fuel bill, but as they say YMMMV.

13% of the total fuel consumed in the USA is wasted idling. How many billions of gallons is that?

regards
mech

Constant speed, no. 5th gear is almost never too tall for 30mph. But if you are going to pulse and glide (which works great at that speed range because your aero drag is relatively small so you can glide for a long time) then 4th may be better.

hate to resurrect this thread but after getting an SG2 the other week and getting some feedback....


I've been able to consistently get 42-49 on the gauge and up doing familiar city routes (lots of coasting and such) BUT

on the highway i can't seem to get over 40, i've tried consistent speeds at 57-70mpg and the best it seems is around 39 average at around 63-65 mpg

this doesn't seem right, i haven't calibrated the sg2 with the second tank of gas but other than that it should be calibrated correctly. My tires are 37psi, it's getting cold up here (michigan).

Not sure if i'm just driving wrong or what's going on, any input?

Air resistance affects the car more at higher speeds.

[QUOTE=doless;459325
My tires are 37psi, it's getting cold up here (michigan).?[/QUOTE]

These two things stick out the most to me.

1. Make sure tires are set to max pressure as listed on the tire's sidewall.

2. Colder temps = less MPG. Significantly less, as I have (sadly ) come to know, as this is my first winter hypermiling. I'm getting 5-10 less mpg, on average. Yikes!