You should consider getting an aftermarket nav like the Garmin Streetpilot. They are everybit as accurate and are portable so you can move them from car to car. Alternatively, you can go with aftermarket such as Alpine's system. This would have the added benefit of allowing you to play DVDs. It will cost around $2K + installation. A bit more than the cost of the nav option, but probably several times the cost cheaper than trying to retrofit the OEM nav to your non-nav car.