Why do they have promos for Nascar on Fox while the race is going on and it is under green?

May be...

It's in the contract they have with NASCAR..
It's stated that FOX has to promote NASCAR..
It doesn't say when.. So FOX is being cute, and killing two birds..

It's so that when there is an accident, you don't get to see it. They need to wait untill a caution flag comes out to run the commercials while they are behind the pace car.

It's all about $$...gotta keep the big whigs in the marketing dept. happy.

Seems like they should just be showing the race. You are already watching Fox. What is a better promo than showing the actual race under green? Why have a commercial to get you to watch the race when you are already watching it?

That's what pays for the free broadcast.

Try wake up people who are falling asleep during the racecar racing forum