Car and Patrol car

Car noun - A self-propelled passenger vehicle on four wheels.

Patrol car and car are semantically related. In some cases you can replace phrase "Patrol car" with "Car", this terms are similar.

Patrol car noun - A car in which policemen cruise the streets; equipped with radiotelephonic communications to headquarters.

Car and patrol car are semantically related. Sometimes you can use "Car" instead a noun phrase "Patrol car".