What you really need to be able to upgrade is the number of parking spaces. In the higher levels, I always had more customers waiting than the available number of spaces. And the services for the cars should be able to be started as soon as they're placed in the service bays, without having to wait for the attendant to walk over to the station, pick up a box, and walk over to drop the box off at the service bay. Other than that, though, pretty good game. I enjoyed it. I especially appreciated the variety of types and colors of the different cars and how realistic they all looked. Well done.