Real Racing 3
I've been playing it for quite a while. Amazing graphics, HUGE selection of cars, customization, multiplayer, etc.
It's not just another racing game.
That's the sharpest picture you're probably gonna get of it without playing the game itself.
That picture might look edited, but that's exactly what you see in a race. No enhancements.
Graphics are unbelievably of high quality.
And it's free.