Tip for those with Autos
 

If you don't want to keep turning the ignition off and on at traffic lights...do put the tranny into neutral. It takes more fuel to "load" the torque converter when it is in drive. My Jeep Liberty Diesel fuels at 15.6mm3 in drive and 6.3mm3 in neutral. With my diesel you can actually "feel" the difference while sitting still.

*mm3 is CFR (Calculated Fuel Rate)

Our 02 Honda Odyssey registers .5gph in D at a stop and .4gph in N at a stop according to the Scan Gauge. Not much difference, but it's sumpin'.

The Cabrio uses about 0.3GPH idling, and I save roughly 10% of idle fuel if I drop it in neutral. Not much, but it all adds up!

Think of it this way: The tranny's in neutral and the engine's free-wheeling at some RPM. Drop it in drive with your foot on the brake. If RPMs stay the same, you're clearly burning more fuel to keep the RPMs up against the load of the immobilized car through the TC.

(Meaning it might not matter as much if the RPM drops when you put it in drive while idling. I think my first (carbed, non-ECU'd) car acted that way... I dunno if anything even remotely recent would, though.)

Rick

Not much! That's a 20% increase in FE :p

Thanks for this post, I wasn't aware if the difference was at all noticeable, but I'll try doing this from now on and see how it goes.

The scan gauge isn't always accurate. For example, I did a trip to California from Mississippi. On my first leg I was coasting with the engine on in N the first 2 legs of the trip. The SG2 reported that this method was yielding about 30mpg for the tank. When I filled it up I had only gotten 25 and 26 mpg. So in closing the only thing that matters is the amount of fuel consumed regardless of what a gauge might say.

popimp, have you calibrated yours? For the past few trips, my scanguage has been pretty accurate.

Yes it's been calibrated. It reports high only when I use the Neutral engine on coasting. If I don't Neutral coast the SG2 is on the money.

I have the same issue too... Even with the engine off - ignition on, the SG reads .3gph :rolleyes:

Does the same go for carb'd engines or just EFI? I don't see how it'd work on a carb, but you never know...