We have heard that NASCAR and Formula One teams are using 3D printing, mainly for prototyping. It appears that Nissan Motorsports is using the technology for a little bit more then just prototyping, however. Today the company revealed that they have been using actual 3D printed parts including a fan housing, as well as a trumpet part for vehicle's intake systems on several of their V8 race cars. More details on this story can be found here: http://3dprint.com/12232/3d-print-nissan-motorsports/

Below are two of the parts which are actually being 3D printed for end-use within their race cars at Nissan Motorsports. The one on the left is the fan housing, and right is the intake part: