Do you use cruise control?

I’ve done lots of Interstate Highway driving over the last year; one particular six-hour stretch of I-10 to be precise. I’ve noticed that many of my fellow motorists seem relatively oblivious to their cruising speed. I’ll usually pick a speed in the 70–85 mph range, set my cruise control, and not touch the accelerator or brake pedal for hours. I inevitably end up in a game of leap-frog with some yahoo who can’t decide how fast he wants to go.

Even if your car doesn’t have CC, it isn’t too hard to set your foot in one position on the accelerator to keep one speed. Why don’t people do this?