Does the speedometer of a car read average speed or instantaneous speed?

Speedometer of car read instantaneous speed of course. Its because when you stop it instantaneous show 0. If speedometer show average speed there should be different value than 0 (much greater) just when you stop.
Maybe there are car with speedometer with average speed but the time from which the average is taken is extremely small. Its simply instantaneous speed.

The geological theory that states that pieces of earth's lithosphere are in constant slow motion is the theory of plate tectonics.

It maybe because uranus is made of gas but uranus has a solid core in the middle