Improving fuel economy for the 1991 200q 20v
alan cordeiro
alancordeiro at comcast.net
Fri Mar 4 22:09:52 EST 2005
Energy used to overcome drag is proportional to the square of the velocity.
(power used is velocity cubed...but gas used depends mostly on energy)
Drag force, Fd = A + BV + CV^2
and energy is Fd * distance.
Unfortunately at low throttle angles the engine is running at lower
volumetric efficiency, overall power conversion efficiencies run
way below Carnot cycle theoretical, probably in the in the
10-15% range, so going VERY slow can also be counterproductive
> You didn't mention anything about aerodynamics. At highway speeds, the
> drag force is quite significant. Hard to say what would improve the
> aerodynamics of our cars....but it could be improved upon. Since drag is
> proportional to the cube of velocity (the power to overcome drag
> anyway), cruising at 60 mph will likely get you better fuel economy than
> cruising at 80 mph.
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