http://www.tvr.co.uk/
The Rosbifs car biz these days is absolutely crawling with companies producing interesting low-volume hardware. TVR and Lotus have their own engines. Morgan and Lotus and some of the others have some very entertaining structures.
Very few ever get to the US; the Morgan Aero 8 is supposed to be coming, eventually.
It helps that the rules on low-volume production type approval are quite loose in the UK. Was reading in one of the Brit mags (think it was a review of the AC 212, a Cobra with the twin-turbo Lotus 3.5L V8) that the exhaust requirements are (a) park the car (b) put it in neutral (c) run the engine halfway to redline and keep it there (d) if the meter stays under 101dbA you pass.