I was talking to my son today about a random theory of a friend of mine. His theory was that speedometers are typically set so that 12 o' clock is the optimal speed for freeway driving in that particular car. So a car with a more powerful engine might put 70mph at the top, while a car with a weaker engine would put say 55mph up at the top.
So... how are speedometer dial ranges set for a given car? Is the max speed set to the fastest the car can reasonably go? Is the preferred freeway speed up at the top of the dial? It's got me curious now -- I know there's wide variations between makes, but there's probably some method to how speed is displayed to the driver.