Re: Fuel economy (was Re: Pressure Acummulator Discoveries)

[Eliot Lim <eliot@u.washington.edu>]

> When my girlfriend went from a
> 5-speed 5-cyl Audi 80 to a 6-cyl, 4-speed auto 90, her mileage actually
> increased despite the 90 being a larger, 400 lb heavier car.  Of
> course, the newer engine management of the V6 and the V6 itself
> deserves some of the credit, but she had a habit of always shifting too
> late (as most people do) for a given acceleration rate, and therefore
> her mileage was very poor with the stick.

i must admit that i too, had a habit of upshifting too late when i had
a 5 speed.  it wasn't until i saw a smart slush in action (coupled with
an instantaneous mpg readout) that i realised how wasteful my habits
were.

one exception though.. my car has torque convertor lockup in 3rd and
4th, and under some situations manually holding 3rd going up a hill
and letting the convertor lockup gets better mileage (not to mention
better acceleration and better response) than letting it churn in 4th.
so there are limits to electronics.. at least as far as my car is
concerned.. this is where the overrides come in handy and once again
it takes an attentive driver to take advantage of it.

john, the comment about wide throttle openings with lower revs being
more economical than small throttle openings and high revs: does that
apply equally and exactly to turbos and supercharged engines as well?

the wildcard in this case is that boost pressure (and thus fuel
injection) is varying...  anyone has an idea?


eliot