Real Racing 3 is well worth a free download and play for ios users. It's the best ios racing game to date by far. You can ignore the store with micro transactions - there is no need if you are even half skilled at racing games.
The visuals are excellent and the handling believable. IGN have a good review on it here:
Real Racing 3 Review - IGN
Until Grid 2 is released RR3 is the best racer so far this year.