Les - I can't recall the exact details of that 4000 but it had a highly-modified 10V 5-cylinder turbo in it along with what I recall was 4:30ish gears. It was insanely fast. Total sleeper car.
I briefly owned a black 4000 quattro. It came as part of the package of 'stuff' when I bought my ur quattro rally car. Normally-aspirated and, man, did that car sound the part (it had no muffler)!!