As a non-native speaker of English, one that I have never grasped is the overuse of the word "vehicle" to mean "car". It's extremely common, but not sure why. It's just a car, why call it a "vehicle"?

I understand it in the very generalized context of, say, the DMV. It's the dept. of motor vehicles because they handle cars but also trucks, vans, commercial haulers, even boats.

But not sure why someone says "I bought a vehicle" when really they just bought a car.