Coming up with an average CA DMV car registration fee isn't a very simple process. The base calculation for a registration fee in the state of California is based on a percentage of the purchase price of a vehicle for new purchases. Cars that aren't new purchases are calculated based on a fair market value. The California Department of Motor Vehicles provides calculators to determine new purchase registration fees, non-resident vehicle registration, used vehicle purchase and renewal registration. All calculations are meant to be estimates, though, because other fees might be assessed based on the particular situation.