How do you play just king and infected?

Not quite sure to understand your question here. Sorry.

He dosent want to race, just play car games. I’m exactly the opposite, would rather race than smash cars. If you look at the tiles when every ones choosing which class to race, in the lower corner are icons for the types of racing featured for that class. If your friends want to smash and crash also you should all choose the race and class that has the games you want to play. You’ll still have races but there will be more games…Charles

If you only want to do King and Infected then you would have to do it in freeroam (if you can get everyone else onboard).