Artemus wrote:

The transmission gear is irrelevant when specifying engine
efficiency. The engine is more efficient at a throttle plate opening
of 1/2 to 3/4. Below this opening the pumping losses around the
plate go way up. Above this and
the mixture gets richer on carbureted engines, FI may be different.

Fuel injection is indeed much different.


Back in the 70's one of the car mags ran an article on a BMW study of
the most efficient acceleration method. The end result was to
accelerate
at 1/2 throttle opening up to 2,000 rpm and upshift. This is
repeated until the desired speed is reached then use the highest
gear, without lugging the
engine, and the appropriate throttle opening. Their data showed that
small throttle openings caused low efficiency, and mpg, due to the
high pumping losses. Long sloooow acceleration times were almost as
bad a jack rabbit start.

A lot has changed since then. Even then, that study was limited in scope
since it did not consider all of the various engines out there at the time.
Today, there are a lot more small DOHC engines out there that run at 6K in
order to hit their torque curve, and lot less pushrod v-8's which deliver
torque just about off an idle. Not to mention that everything is fuel
injected today and nobody manufactures a production carburated engine.

About the only thing that hasn't changed is that nobody likes to get stuck
behind that guy that believes it's better to accelerate slooooooooly....

--

-Mike-