This was interesting to me because it illustrates the penalty of weight when a car is navigating corners. The clip on the right is Randy Pobst driving a Porsche 918. On the right is my street-driven 1972 911. Pobst is setting the production-car lap record at Willow Springs with this lap. The 918 has already set the same record at the Nurburgring. It is arguably the fastest production car ever made.

Now, it's important to note that the 918 is almost 4 full seconds a lap faster than my car at Willow Springs. But when I just look at the more technical part of the track -- from the turn 2 sweeper through to the 3-4-5 combination -- the two cars were essentially dead even. The 918 has 887 horsepower. My 911 has 272 horsepower. The 918 has better tires and a better driver. But my 911 is 1000 pounds lighter than the 918, which allows me to make up some of the performance gap when both cars are not going in a straight line.

Mass is mass, after all.