It depends on the city code. In my county "junk cars" are not allowed at all although that's not super clearly defined, car repairs aren't allowed at all unless

It depends on the city code. In my county "junk cars" are not allowed at all although that's not super clearly defined, car repairs aren't allowed at all unless in "an enclosed building", and you can't have more then a certain number of cars visible from the street. That said - last week my neighbor had his car up on a jack, in the street, for 2 days straight. He was repairing something under the rear of the car in cold weather. He's "allowed" to do this because none of us are mean and called in a complaint so the city didn't know about it.