Car auctions - buy old cars and renovate them. You can then sell them for cash or have your own collection.
The photo mode - take "before" and "after" pictures of the renovated cars.
Visual tuning - replace bumpers, lights, wheels, a bonnet or a steering wheel to adjust the car for the customer's needs.
Repair cars for your clients - it is your main source of income.
An infinite number of randomly generated missions.