I don't think we should get rid of all the cartoon cars, although we need to be more selective. Some of them are well-drawn, and meant to be a very specific car. However, many are generic blobs that we've identified anyways (such as just about every background car in "Cars").

As for the scooters and wheelchairs, they're a bit of a stretch, from that point, we're not far from trying to identify bicycles or rollerblades.