9FF is a German car tuning company, based in Dortmund, founded by Jan Fatthauer in 2001, specializing in converting stock Porsches into street legal racing machines, either as fully tuned cars, or selling individual parts or kits. They are best known for building one of the first cars to exceed 400 km/h (249 mph) - the GT9, which is capable of speeds up to 256 mph (412 km/h). The former company, 9ff Fahrzeugtechnik GmbH, filed for bankruptcy in September 2013. The 9ff Engineering GmbH, founded in October 2013, continues proceedings.
- As with the RUF cars and the Rinspeed zaZen, the 9FF GT9 VMAX became unavailable for purchase after the Porsche Update, due to licensing obligations with Porsche. This resulted in the Winter Came collection becoming impossible to complete until the Munich Update.