Mustang Parts
   Carrying Saleen wheels and Bullitt wheels.

Saturday, June 02, 2007

Comparing Cars--SpD

Recently, MotorTrend tested a bunch of high performance cars, and presented the results as spiderwebs, with a combined performance number based on things like steering accuracy, brake feel, roadholding, etc. The result was neat, but not practically useful because it didn't factor in cost.

Then Winding Road got in the game, and proposed the Speed/Dollar index, which is HP/weight/price * fudge factor.

A problem with the SpD metric is that it only cares about power/weight ratio, which can favor cheap cars with big engines, such as the Mustang GT, or even a V8 Chevy family hauler. Nice in a straight line, but what if you are interested in autocross or rallying?

I think a better metric would be something like (HP/Weight + Slalom Speed/60)/Price * K, which would add a dynamic handling component--the speed through a slalom course, in this example. Or perhaps a lap time or average speed around a reference track would be better.

Both Winding Road and Motor Trend put the MazdaSpeed 3 near the top of their list, in terms of bang-for-the buck. Now I want one.

1 comment:

Anonymous said...

As much as price matters to everyone, it matters differently to everyone. I think Consumer reports gets it right: rank things without regard to price, then go as high on the list as you can afford. Car and Driver mistakenly added price, and I now have to back out the influence to find out which car really is better. If a guy can afford a Porsche, shouldn't he know that it's better than the Corvette, say? Of course it's more expensive, but if that were the overriding issue we'd all be driving Yarises (Yari?).