If that was ever true it might have been when they actually raced cars that were at least similar to the cars that you could buy...eg Trans Am in the 60's and Stock Cars in the 50's. NASCAR is whistling past the grave yard now, there are not 15 teams that have budgets to make them competitive. To hear the double talk by the big three about the need to market thru NASCAR is just laughable, it is simply boys and their toys. If you can name a car that increased market share by racing (Porche, Ferrari) , I can name 20 that had great success and are now long gone. Both Hendrick and Penske are very big dealership companies. The dealers are in big trouble. Penske is a public company (PAG) and you can look at their filings, it isn't pretty. Roush is very dependent on the auto industry. I can not believe that the big three, or even the big 4 if you include Toyota will be able to justify to their stockholders the cost of racing. I understand Honda is out of F1. I would not be surprised to see racing return to it's roots and I for one think that is a good deal.
