Ruf Automobile is a German automobile manufacturer founded in 1939. Originally started as a service garage, then later producing buses, Ruf changed direction when the founder's son, Alois Ruf Jr. took control of the company. An avid car enthusiast, Ruf Jr. began to modify and restore classic Porches, leading the company to specialize in customizing Porsches, mainly the 911. Eventually Ruf took some of their modifications to an extent that they are considered their own manufacturer. Models such as the CTR Yellowbird and the RtR are notable examples of Rufs. It's possible to distinguish between Ruf manufactured cars and Porsche tuned cars by looking at the VIN. A Ruf VIN starts with "W09" while a Porsche VIN starts with "WP".