Try this:
Alternate Starting Point
While selecting a driver hold the gear shift in reverse, press start, select a driver, and then release the gear shift.
Sorry it's not anything exciting though... You can also get a quick speed boost by doing this, it's not really a code though.
Speed Boost
During gameplay release the gas pedal, quickly shift into reverse, then back into drive and floor the gas pedal.
I'm just wondering, what kind of racing wheel and pedals do you use?