Autonomous

I originally posted about converting a John Deere Power Wheels tractor to remote control powered through the RPi. I decided not to for various reasons. Time was one of those reasons. Now, I have been able to come up with a large scale electric remote control vehicle. I'm looking to hook that up in a collaboration with the Raspberry Pi. I have some ideas but just wanted to get some opinions and maybe even a difficulty rate as for as programming and so forth. Any help will be much appreciated!