It's not really a flamethrower, it is a propane-fired burner which simulates the exhaust from the jet engine by which the TV version was supposed to have been powered. It's only sort of a glorified propane torch but turning that thing on while driving would undoubtedly attract most of the police in the area, I'm sure. Really good pix and info can be found here:
http://buybatparts.com/joomla/index.php/replicas