Depends on the insurance company and depends on which state you live in. Call & ask. We called ours & the agent told us how to list drivers vs. cars to get the best deal. He doesn't want to lose your whole family as customers.

But if there's a car for each driver, they probably will not let you get away with NOT being listed as primary driver on some car. A friend said his insurance made them list his teenage daughter as primary driver on the most expensive car in the household. Didn't matter who was the registered owner. (They're shopping for new insurance...)