On this episode of Head 2 Head presented by Tire Rack (http://www.tirerack.com), Jonny Lieberman and new cohost Jethro Bovingdon go on the ultimate gearhead road trip in Germany and Austria—from Autobahns with no speed limit to the wild Nürburgring race circuit, and finally a mountain pass that climbs to a stunning glacier. The contenders? Well, it had to be the two iconic German sports cars: the BMW M4 and Porsche 911. The brand-new M4 CS is lighter, more powerful, and more focused, but can it really compete with the brilliant 911 GTS? Watch and find out!