Project: The Anal Probe

[Sven7]

In case anyone was wondering how much idling and engine ON coasting affects mileage, I filled up today and got 35mpg. Probably a 5mpg drop.

By the way...
(NSFW lyrics)

http://www.youtube.com/watch?v=Lr0XEcUmD4s

[MetroMPG]

35 vs 40 mpg = 12.5% lower.

Coincidentally... (?) my own unscientific observation on the same question was pretty darned close. In the Firefly: 53.4 vs 60.3 mpg = 11.4% lower.

Coasting experiment: engine off VS. engine idling - MetroMPG.com

EDIT: from this we can see why automakers really want the EPA to devise a way to take into effect engine start/stop systems (on non-hybrids) in the city tests.

[ps2fixer]

Interesting results, what about in gear fuel cut coasting? I think I read it was better than neutral coasting but not as good as engine off coasting.

Also how do you get back up to speed, I have read you want load at 80%, but doing so makes my auto want to kick down, so I'm fighting trying to keep 80% load vs keeping a higher gear.

[MetroMPG]

That's probably an "it depends" answer.

Fuel cut (DFCO) deceleration means you'll go a significantly shorter distance than if you neutral coast while idling, so I doubt it's as effective as neutral coasting (because you need more fuel prior to DFCO to cover the same total distance).

I only DFCO when I *want* to slow down more quickly (ie. engine braking). (I don't drive much in hilly territory where I'd use DFCO as a technique to control downhill speed.)

I've never seen any controlled attempt to compare the two approaches. Besides, I suspect the results would vary greatly from vehicle to vehicle, which just makes it an "it depends" situation. No pat answer.

[euromodder]

Originally Posted by ps2fixer

Interesting results, what about in gear fuel cut coasting? I think I read it was better than neutral coasting but not as good as engine off coasting.

If you stay in gear you're braking, thus covering less distance.
That makes it less efficient than coasting in neutral.

Coasting in neutral has significantly reduced my fuel consumption - it's now my main way to slow down.
I avidly used DFCO / engine braking before joining ecomodder.

Coasting in neutral or engine off will really add to the benefits of aerodynamic improvements - you'll roll ever further.

[Sven7]

I rarely hit high enough revs to get DFCO, if this car even does it. Today I started engine braking but I'm not sure if it is more or less efficient than neutral coasting with friction brakes.

How do you guys change gears during engine braking? I feel like it's probably harder on the clutch than bump starting.

An MPGuino would be nice.

[Sven7]

a friend sent me this

Beaterblog Marketplace: Beat Worthy: Aero Modded Ford Probe

[FXSTi]

Tyler,

Damn you, I just spent an hour reading that blog

[Sven7]

No real updates. I haven't been driving much except for short trips. Washed it in the rain a few days ago and the honey badger flaked off- it's getting more and more tempting to waste a few hours with painters tape and aerosol to finish the dazzle paint job.

I've got another alternator and some rear brake pads to swap in when time allows but this weekend was ruined by a cold. Good news though- today I scored a bunch of corrugated cardboard and some light aluminum angle iron out of the dumpster.

It will be good for a boattail mockup

[ps2fixer]

I can't wait to see your boat tail when finished, your other mods look good, so a good looking boat tail would encourage me at least to attempt it. Hoping you get 50-55mpg with the boat tail with summer driving .