I just recently discovered the Dauer 962, when I was doing some research on twin turbocharged supercars of the 80's and 90's.
It has a twin KKK turbocharged Porsche I6, that outputs around 730 HP, and has a top speed of 251.6 MPH, and did I mention it was made back in 1994?
Sadly though, it couldn't qualify for fastest production car, as there was only 14 or so produced, however it did win the 1994 24 hours of Le Mans, in which Dauer entered using a loophole, and it was also one of the last Group C cars ever built.
I brought this car up in the McLaren P1 thread.
It is also one of my favorite cars and it's probably one of the fastest street legal production cars ever made. It might even be the fastest street legal production car ever made, the one car that may be faster is the Caparo T1 but the Zonda R set a faster time than the T1 on the Top Gear test track. Not that I really think Top Gear lap times mean very much, but I think the Le Mans could be faster than the Zonda R.
Anyway, the Dauer Le Mans was actually the fastest (top speed) production car in the world. Even Gordon Murray admitted there were faster cars than the McLaren F1. In a letter to Evo Magazine Murray stated:
"Firstly, our records are only valid for a true production car which has passed full EEC type approval and emissions testing. There have been several other low volume specials (such as the Porsche 962) that have acheived a higher top speed."
So basically he's saying the 962 is a faster car, but didn't have EEC approval or admissions testing. That is completely irrelevant though because the Le Mans was declared road legal by TÜV, which is much more important.
The only reason it's not commonly listed is because it's either not widely know or, in the case of Wikipedia for example, they only list cars with production numbers higher than 20. I don't really agree with that because I think as long as the car was produced for sale in a quantity greater than one, and it was sold multiple times I think it should count as a production car. Jochen Dauer was actually expecting/hoping (or was at least ready) to sell 50 Le Mans but of course he only sold 12-14 (Official brochure says 13 I believe). The Dauer Le Mans is a production car and was the fastest car in the world at the time of its release.
There were also other street legal 962s, though the Le Mans was likely the best one.
The Koenig C 62 had 800 PS (though it's commonly mistaken to have 588 HP/PS but that's actually KW. 800 PS converts to 789 horsepower, which then converts to 588 KW.)
There is also the DP62 which has 600 horsepower.
And finally there is the the Schuppan 962CR which looks quite a bit different than the other three and also has 600 horsepower.
I apologize to the mods and admins if I am not allowed to post this, but here are some articles about the car:
http://car-builds.com/showthread.php?148-Dauer-Le-Mans-and-Koenig-C-62