Ah yes.. when I was 14, my father let me drive his Ford Aerostar minivan in a parking lot of a department store. It was like 6 AM on a Sunday and there was one other car there in this lot of about 250 spaces. I still managed to come within 3 inches of hitting it, not before accidently driving onto a median.
Dunno what happened between 14 and 16, but I guess some part of my brain that processes spactial thinking improved so much that I was able to drive (fast, even) pretty much from the second I returned behind the wheel - of the Nissan Sentra used at driver's ed.
I definitely wouldn't trust a 14-year-old with anything more than a bike.