I found this today on a Mini forum. Kinda interesting. It's a do-it-yourself G-meter that you can make from parts scored at Radio Shack:

http://zedomax.com/diy/102/diy102.htm

Cost is about $188 all together. Not really cheap. But it's a learning experience I guess. :)

Would there be any way that you could set it up to datalog and upload to a computer for lap comparisons? I'm also curious if it could be tapped into the drive by wire to determine steering angle and throttle position, even cooler would be acceleration and braking.

My radio has one of those. I love it.