Any car in proper condition can be used. We are not a taxi company, but a carpooling community. Wunder is like giving a ride to a friend. Therefore, there are less restrictions. The car should be safe and insured, for sure!
And if you want to get good ratings from your riders, try to keep your car clean and smelling fresh! If you have a very stinky car, it might be a good idea to get some air freshener!