The autobahn was great. Miles and miles of perfectly smooth pavement. By law slower drivers must move to the right. I think I dented the floor boards on the rental trying to get an extra MPH.
I'd be nervous driving some American muscle around. You can get into some tight spots in a hurry. In Sevilla I missed a turn and had the road narrow down and scrape both mirrors on a chevy spark. The suv ahead scraped the whole body. Of course the beaches of southern Spain more than made up for any stress while driving.