Well you can make a RC-(Bluetooth, WiFi, Radio) system for any car, no matter how old it is, then you can control the car with any phone.. N95, N900 etc....

If you just want to turn it on, control lights, horn etc.. then Bluetooth Relay system is an easy option to use, then make you own program (app.......) to control it, again every phone/device with bluetooth can do this.

http://www.youtube.com/watch?v=FoXBb6JoSv4