Couldn't you swap a PRO class (PSB) for an up and coming class (PM)? I would think more people would stay in the stands to watch PM instead of PSB, isn't that the goal? What brands work on a PSB bike that wouldn't work on a PM car? (other then Harley, Suzuki).
From what I see, people in the stands are definitely a goal but it's fairly far down the list. I'd say that the upfront money is king right now and any gate money is just icing on the cake.
Part of that may be because of the way a National Event's money is split between the NHRA and the host track. I don't know for sure, but I'm guessing that the NHRA would much rather have a specified amount of class-sponsoring money paid directly to them rather than sharing a highly variable amount coming from admission.
Why bikes and not PMs? I agree with previous posters in that the bikes don't take much time to run a session and rarely oil the track. But the real kicker here in my mind is the Harley money. Ain't no telling how much changes hands but I'd bet it would surprise a lot of people. Besides, bikes have a long history with the NHRA from back in the day when a Triumph Bonneville was the quickest thing on the street, through Top Fuel Bikes, to the present day factory wars.
Trust me, if Kia decided to back a class for alcohol burning Souls and signed a multiyear contract for a boat load of money with corresponding advertising and team support, a place would be found for them.
And they might even join the Pro ranks.
For those still confused about Pro vs Non-Pro, off the top of my head:
Pro classes race at every race during the Pro session.
Pro classes are promoted as one group by NHRA Media Relations and Marketing.
Drivers in Pro classes will be the ones making the appearances, press conferences, and TV spots when a race comes to town.
Pro classes are the core of what NHRA sells and what they brand.
Non-pro classes sometimes are described as exhibition classes.
Promotion is done by separate press releases and campaigns.
They race in their own sessions and can be bumped if needed.