Weight reduction - not always good?

[landspeed]

Originally Posted by bbgobie

Drag would be the same on heavy and light car.
Assuming no rolling resistance the force to keep both cars at a constant speed is the same isn't?

So the variable is acceleration, and F=ma. Maybe I'm not getting it, but I dont think there is a sweet spot, or at least not a realistic one that can be reached. If you could strip 10% off the mass of your car, I dont think it would be less efficient, except the winter driving case.

The three variables are:

Rolling resistance ( = weight * rolling_resistance_coefficient)
Momentum (is proportional to weight) (related to kinetic energy)
Aero drag.

So, the heavy car means you can 'charge' up the momentum, and then coast for ages, whereas the light car has no momentum to charge.

I suppose what I'm saying is that....

If you could half the RR coefficient on the tyres *OR* half the weight of the car,

then you should half the RR coefficient on the tyres - because then you will have half the RR but the same kinetic energy which you can use in a 'hybrid' fashion.