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.