If someone (truthfully) says "I have a car" then they have at least one car. If someone says "I have one car" then they have exactly one car.
How does this idea work for "我有一辆汽车" ?
- Could someone say this just to indicate that they are a car-owner-- i.e. they have at least one car? If so then how would one instead specify that they have exactly one car?
- Or would saying this indicate that they have exactly one car? If so, then how would one instead make the more general assertion that they are a car-owner?