How much better is lighter?

[COBRANIP]

DocDirk, I have the same curosity and am working (?) on a similar project but am not far enough along to shed any light. I am starting with a Herb/Matt Adams aluminum frame (200 lbs) and a FFR carbon fiber body (probably under 100 lbs). I am looking at it primarily as a track car. There is no doubt a heavy car will have a more comfortable ride (assuming a relatively heavy sprung weight to a relatively light unsprung weight...that is simple physics).
One other benefit is for any given HP/WT ratio the lighter car will require less HP... which I think can translate into a "more reliable" and less extreme engine.
The biggest problem I anticipate is traction. As you get lighter and lighter how do you get the power to the ground?
I really enjoy the engineering challenge which is my motivation.
I would think the biggest advantage would be in something like an Autocross course.

[Snake2998]

The simple answer is that on the track a well engineered light car will be faster in every way, except maybe acceleration, than a similar well engineered heavy car given the same power to weight ratios.

On the road it doesn't matter nearly as much because to overcome weight you can just add power - that might mean adding more weight and cost but then adding lightness is also normally very expensive in it's own right - especially if properly designed and engineered.

[Excaliber]

One of the problems with a light weight glass body would be durability issues. Spider lines in the paint from stress for example. Shakes, vibration, twisting issues would be more evident, cracking easier on light impact.

Recently had a chance to compare the thickness of a Classic Roadster to an FFR, whew, it's night and day when it comes to structural integrity. Of course the penalty for the C.R. is a weight gain. There is no free lunch.

[Buzz]

Originally Posted by COBRANIP

The biggest problem I anticipate is traction. As you get lighter and lighter how do you get the power to the ground?

Weight over the drive axle comes in handy traction-wise when a vehicle is stuck in snow or sand. For acceleration and applying power when exiting a turn, a lighter car has less mass to heave into motion and is less hamstrung by inertia. In other words, a lighter car with the same power will accelerate away from a heavier one off the line with less wheelspin simply because the tires have less dead weight to struggle against.