NASCAR speedometers

They don't have them. I didn't know this. But this blog says it is so. Interesting. My dad used to always install a tachometer in our cars whenever they came without one. As a kid, I just thought it was cool to see how close the engine got to the redline, I never really thought about what it meant. As an adult, I would (if I had one) use the tach to ensure that I'm avoiding jack rabbit starts and maximizing gas mileage. Apparently there's more. As it turns out, though, you can also use the tachometer to calculate your speed. Who knew?

Well, my dad. And NASCAR. The theory behind this, though? Can anybody explain how it works? It seems like you have to know the relationship between one revolution of your engine and one revolution of your wheel. Is that right?

Anyway, even without knowing that fact, I think I'm going to start reading NASCAR blogs. I mean, I can't think of anything more boring than watching people drive in a circle, but maybe I can garner some insight into the sport through this secondary viewing method. I'll report back later with my results.