I've done B, A, IC, and IB all gold with a Sixaxis, with the sole exception of IC-10. That one seems doable as well. The run where I got silver, I was about 1.5 seconds behind the first place car, and I know I gave up 1.5 seconds through mistakes on that run.
I'll be starting in on IA licenses shortly...
I'll be starting in on IA licenses shortly...