Here's my take on it....

Rather than a foolish race for a car worth hundreds of dollars that will end your relationship and probably get the looser grounded, why don't you bet that the looser is the winners pit/wrench man for a month or two. Anything that needs fixing, cleaning or tweaking the looser needs to perform it on the winners vehicle. This way it's a win win situation... it's a fun race with a friendly and educational outcome. The winner gets bragging rights, while the looser gets the experience of working on someone else's vehicle and now has additional skills in their pocket...

Think about it... and let me know what you think... I do it with my kids all the time and yes... I've been their pit/wrench ***** a bunch of times... LOL...