All depends on whether this specific Ford Fusion is being sold by Car Max as a new vehicle or used. If it's being sold to a private party for the first time, the vehicle will be considered "new" and will not be allowed to receive California registration because it is a 49-state vehicle. If it is being sold as a used vehicle, meaning it has previously been registered to a private party and now being sold to you, than the vehicle will be considered "used" and can obtain a California smog check as a 49-state emission vehicle. Upon passing the California smog test, it will be allowed CA registration.
We highly recommend getting very specific registration information from the seller, and in writing. Also contact the California DMV for final approval prior to purchasing this vehicle.