Ron Patrick converted a 1350hp T58-8F helicopter engine and installed it on his Beetle. Here is some words from designer:
This is my street-legal jet car on full afterburner. The car has two engines: the production gasoline engine in the front driving the front wheels and the jet engine in the back. The idea is that you drive around legally on the gasoline engine and when you want to have some fun, you spin up the jet and get on the burner (you can start the jet while driving along on the gasoline engine). The car was built because I wanted the wildest street-legal ride possible.
via: Ron Patrick