Eventually, you'll have to register the car in the state it is being operated in. I believe there is a limited number of days that out-of-state plates can stay on a car being driven in California. In other words, if you drive it here and you are a California resident, you must register it here. If the person who owns the vehicle lives in FL, but the car is being regularly driven in CA, he must register the car in CA.
If you are a CA resident who wants to register an out-of-state car in CA, the car must (1) have over 7500mi on the odometer and (2) meet emissions requirements. If you are a non-CA resident when you bought the vehicle, you can bring your car in regardless of mileage so long as it passes emissions. Your drivers license will reflect your residency.
Be careful, if you try to register the out-of-state car at a CA DMV, and you are (for whatever reason) unsuccessful, your car will be banned from California forever. Read: FOREVER. It's a one-strike deal. You would have to get rid of it somehow (sell it to someone in another state) asap.
http://www.dmv.ca.gov/pubs/brochures...cts/ffvr29.htm
I had an issue with this last week and it was a nightmare. Fortunately, I succeeded.