This is supposed to be the best racing/car game for the iPhone/iPad and was recently released. It includes the Boss. Downloading now and will report back after my son checks it out.
https://itunes.apple.com/us/app/need-for-speed-most-wanted/id540925164?mt=8
https://itunes.apple.com/us/app/need-for-speed-most-wanted/id540925164?mt=8