I just spent 4 days driving a Baja Challenge car back in January from Ensenada to San Felipe and back again. In a word, it was AWESOME!

You can do the trip through Wide Open Baja and as they put it "will give you enough rope to hang yourself with" driving the car. You're basically running the Baja course with a guide rather than blind, but at full speed. If you do it, absolutely get the optional insurance. You pay for anything you break.