I've got a few ideas:
1) Have a couple of special figure 8 races, like the ones at the county fair, where drivers have to turn both right and left and make quick judgements about when and where to shoot the gap
2) Build an optional jump section on the back straights of the longer speedways--take the jump, get five points. Or maybe a cool loop-the-loop like Hot Wheels, worth ten points
3) Speedos-and-sunglasses competition during a Nascar-mandated 'safety halftime' where you can vote on a Sprint phone. Random winner gets a peek in the Speedos (but not behind the shades)
4) Give each driver a bucket of debris that he can throw out on the track when he needs to go wee-wee or gets really angry at some other driver
5) Equip the cars with radio controls and let the spotters do the driving, making all of the 'drivers' available for interviews during the race
6) One pit per team, like in Formula 1, with no limit on how many guys can go over the wall
7) Allow fuel injection, disc brakes, and independent suspension for any car that adopts front-wheel drive
8) Keys-in-the-bowl races, where each driver selects his ride at random
9) Close the pits during commercial breaks--I mean,'cautions'
10) Rain tires