Zip-Lock - You could have just added some external RAM. I know it sounds like a pain in the butt, but I do it all the time. And while you were at it you could have added some EEPROM for data logging. So when one of your buddies/kids/wife/g-f/etc. borrow the car, you can see where they took it.
It's also good for making your own maps, and whatnot.