Do Speedometers Lie?

The Puzzler

RAY: Here's the answer: Because when I looked down at the dashboard, I not only looked at the speedometer, but also the tachometer. Both of these cars redline at about 6,000 rpms. Anything over 6,000, you're in danger of having the pistons become part of the environment. At 60 mph, the BMW was doing 3100 rpms. I knew that at 120 mph it would be beyond the redline and incapable of doing 160 mph. 6200 rpms only got me to 120. So I knew I was going to be well into the red zone and probably decorating the highway with pistons. The Mustang Cobra at 60 mph was doing less than 2000 rpms -- it was doing about 1750 rpms. It turns out that we called the Ford Special Vehicle Team and they said it wouldn't do 160 mph. I was able to get it to 155.

[ Car Talk Puzzler ]

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