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)
2006 Jeep Liberty CRD...Founder of L.O.S.T.
OME 2.25" Lift w/ Toyo Open Country HTs 235/75/16s
ASFIR Alum Eng/Tranny/Transfercase/Fuel Skids
2002 Air Box Mod...Air Tabs (5) on Roof...(3)each behind rear windows
Partial Grill Block with Custom Air Scoop and 3" Open Catback Exhaust
Lambretta UNO150cc 4 Stroke Scooter
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.)
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.
Originally Posted by theclencher
P.S. I must be a wierdo as I think just because a guy can afford to do something, doesn't mean he should. I can afford to buy 100 gallons of gas several times a month, pour it on the ground, light it (or not)... but I don't think I should.