The State Patrol car was actually the first Chevrolet Impala from Corgi, issued in December 1959. This particular version, however, comes from the very last of the model produced in 1965 when free-spinning wheels were fitted. Before that you'll find that the vast majority of these models had wither fixed smooth wheels or the fixed shaped variety.
Although it does not look it, this is, therefore quite uncommon.
This example has been well played-with as you can see but it is all original and even has the original aerial which most lose at some point. It is missing the paper stickers on the sides but these are easy to find reproductions for if required.
As well as several areas of paint loss there is a crack in the front screen. It does still look nice on display, however, and may fill a hole in your collection until a better condition example comes along.