Because each race is 3-4 hours long, is watched by millions, and is full of their name being thrown out.

How much would it cost to basically advertise during the duration of an NBA playoff game.

It's just cheap exposure for their brands no matter what the car looks like just as it is for the teams sponsors. Kevin Harvick won the race Saturday night and all you could hear was "shell-pennzoil" "shell-pennzoil" shell-pennzoil" even though the car doesn't use Shell gas and Richard Childress engines possibly might not even use Pennzoil in their engines.

 

I thought the 3 ponycars were all "coming" to Nationwide for next year,a friend told me this and I hope it will happen.....even if it's a vague look of the 3,having it called Camaro would make me want to buy the merchandise that goes with it..some exposure is better than no exposure

 

Sure, I can see Tide or Viagra paying for a rolling billboard. But I haven't seen any evidence that the "race on Sunday, sell on Monday" rules apply to cars anymore with NASCAR. I mean no one will look at the headlight decals on a NASCAR template car and say, "oh man, I've got to buy a Taurus or Impala after seeing those".
A FAR cry from what NASCAR used to be....

 

FWIW the body templates used in the new Nationwide series cars seems to be more manufacturer specific than the Cup cars. I thought the Challenger looked very similar is shape to the production Challenger, although I agree that the mustang deviated significantly from the street car. That being said I like the look of the new nationwide cars much more than the cup cars, and I hope that in the near future the cup cars will change to a more appealing body style with some subtle differences between manufacturers.

And I think it would be cool to see the Camaro body in a NASCAR race.

 

NASCAR has fought for too long to get a standard spec template COT to go back to manufacturer specific bodies in the Cup cars. They have the spec racing series with manufacturer support that they always wanted. NASCAR will allow the manufacturers a different nose and brand name in the Nationwide series but never Cup. It's their way of giving the manufactures a bone because they have been pushed into the standard spec COT in Cup.
The Nationwide Mustang is a complete abomination. I'm surprised Ford wanted to put their storied Mustang brand name on that. It's a disgrace. The Challenger is better looking and closer to the production look but I would have to think aero suffers a bit with that nose.
Just looking at these cars I can see why Chevy wouldn't want the highly styled Camaro to be almost maimed as just a nose on a COT car. I could also see GM playing with both the Camaro and Impala COT in the wind tunnel. In the end they didn't have to compromise the Camaro brand identity and stayed with what I would think is a better aero COT, Impala.