RTT Germany recently released a short animation using mental ray for the exterior shots.
From one of the artists involved on the project, Adrian Chifor:
The unified sampling also allowed me to have 3d motion blur and the biggest render time was no longer than a couple of hours with most of the frames rendering below 30 min per frame. Since the lighting was very simple the render times were never an issue. As far as passes I only had the beauty and on some shots I used an AO pass. I think for one shot I used a normal pass for a post relighting tweak, the rest were just masks and shadow.
Take a look at the finished animation below as well as the RTT Showreel here: RTT Work