Because its a Mustang
In the Mustang crowd, as long as you know how to take care of your car, nobody cares how many cylinders you have A friend of mine has a red '02 GT and his car doesn't get NEARLY as many compliments as my V6 does simply because he doesn't know how to take care of it.
Well of course it's no fun if you just do the required races and nothing else. You have to do ALL the races and spend lots of time customizing your car. Sometimes I spend more time changing body kits, paints, and vinyls on my car than I do actually racing. I also like to drive around and find some cops to piss off, just because it's fun.