At 09:56 PM 3/24/2012, Roland wrote:
>consumed in 3rd gear vs 4th gear?  Now the immediate answer is none!  It
>takes the same energy to drive at 45 mph in 3rd or 4th.  The wind
>resistance is the same, the drive-line loss is the same, other friction
>like tires are the same.

But it takes more energy to run the engine faster.  The inertial
losses from reversing the pistons' direction of travel, the
frictional losses from scrubbing the piston rings up and down in
their bores, the energy lost by compressing the fuel/air charge and
operating the valve train, the additional output of the water and oil
pumps - these parasitic losses all increase more-or-less linearly
with increasing rpm.

It would be interesting for someone with an OBDII engine to do some
calculations of no-load operation at various rpm, using the rpm and
engine load numbers to determine the relative amount of fuel required
to merely spin the engine at those rpm.  I wish I'd done it while I
still had my Honda.

Yours,
David