Vuber is the number one car sharing app game.
Register your account, then start driving around town waiting to be matched with a rider. Accept the ride on your phone, and then go pick them up. See how much money you can make. But riders are a fickle bunch. To keep driving you will need to keep your rating up. And to do that, you will need to see the riders happy.
Finally, ride sharing comes to the iPad in game form.
This is purely a game, not an actual way to make real money.
No ads, no in-app purchasing. One payment.