Gaming company Polarbit is the grandfather of iPhone racers. Raging Thunder was among the first racers to hit the iPhone. Reckless Racing was released soon after and now it's back as Reckless Racing 2. This is a full update to the isometric driving title. The gameplay is similar to other top-down titles like Death Rally, though more realistic. Think of a fun game with a hardcore driving elements to set your expectations.
Career mode lets you climb the competitive ladder, upgrade parts and advance in the the Performance Index. The driving is more traditional than Reckless Racing. You'll still make powerslides and jumps, but you can also follow the driving lines closely and advance technically. Online and offline multiplayer modes are available, as are ghost runs and leaderboards.
Reckless Racing 2 is an excellent update from a developer who loves racing games. It's currently US$4.99 for a universal version, which might be more than you're willing to spend. Fortunately, Polarbit is generous with the sales, so keep an eye out for a price drop.