Dude, we were just up there. Riding and 4X4 down this same trail. It was a blast. Driving back up this particular spot was tricky with our bikes on the back of our 4runner.
Yes, we drove all the way to the top of the Big Boulder trail, then rode our bikes down into Downieville. It was a blast, but on the last day I ended up OTB, which put me in the Grass Valley hospital for 3 days.