Blacktop on Garage Floor??
The main implication is that the asphalt will walk off on to your shoes and be tracked on your floors. This is a real problem that stains most light colored vinyl floors and carpets, of course.
If you like the house, you should consider removing it. I think it was a silly move who evers bright idea that was. I might also be dangerous, (if it's attached to your house), especially someday when you decide to apply a sealer/dressing on it. I bet there is a code against it?