Does a car's speedometer measure speed, velocity, or both?

Question

Does a car's speedometer measure speed, velocity, or both?

Answer 1

It measures speed.  Velocity is the speed together with direction.  

Answer 2

A cars speedometer measures the rate at which the wheels spin, which is correlated to (using an assumed diameter for the tires) a speed over the ground in miles per hour or kilometers per hour. The speedometer only gives direction as "forward" therefore does not truly represent velocity, which is a combination of speed and direction. A common feature of many speedometers (all that I have ever heard of) is an odometer, which measures total distance traveled, a good indication of the wear on the vehicle.

Answer 3

Well a speedometer measures miles per hour, or kilometers per hour, therefore only measures rate of speed.  

Answer 4

I was reading the answers and I was amazed no one picked up on the fact that it is a SPEEDometer.

Velocity is a vector quantity so for it to measure velocity it need to measure speed and direction.

Speed is a scalar quantity so direction is unimportant.

Answer 5

It actually measures the rate at which the wheels spin.