That's not what vendor lock-in is about. Lock-in means that after you bought it, you can't reasonably switch to something better, something that commonly you didn't know about or that didn't exist when you made the initial buy. For example, when offering integrated services, lock-in might mean that they won't allow a third party to integrate with their suite.
No. For the car example, lock-in means you aren't able to use off-brand accessories, or service your car in an unlicensed shop. However, cars are mostly self-contained, so this mostly only comes up with aftermarket stereo systems and membership programs.
And yes, mild lock-in is very common. That doesn't make it a good practice from the consumer's point of view.
http://en.wikipedia.org/wiki/Vendor_lock-in