This is the 2nd year and I think the defending champ is driving another car make. But I don't know for sure. Someone else is renting leo's 68 car. And for svt not being favored, it won 3/4 races this year. There are also adjustments to be made to equalize the cars.
If you want to race NASA then spec focus is the way to go for the money. Nice thing is if you want something faster you can hop in performance touring. NASA says bring a car, and we'll find a class for you to race in.
Your last fear should not be this becoming too popular. Leo is bringing 3 of the 5 cars and did the cage on the 4th.