i do believe theres only 4 black cars..... am i wrong?
Well, technically speaking there are hundreds of black cars in GT4.
Now if you are talking about the LM cars that are only available on the 100th week in the used car lots, then yes, there are only four.
There were rumors that the black 2001 Honda S2000 Type V and 2000 Renault Clio Sport V6 24V that also show up on the 100th week in the Used Car II lot were also "special black cars".
They do show up in that lot directly above the black Nissan R390 and Toyota GT-One, and because the Renault is a 2000 model car, and the cars in the lots, except the black LM cars, are all sorted by year did suggest that maybe they were special black cars as well. However, upon closer review, one can quickly see they are not so special after all.
The same "Noir Nacre" colored 2000 Renault Clio Sport V6 24V shows up in the used II lot a total of six separate weeks (25, 28, 32, 67, 96, 100), and all the 2000 Renault Clio Sport V6 24V are sorted incorrectly in the lots as if they are 2001 model year cars... likely another small oversight by PD.
The "Berlina Black" 2001 Honda S2000 Type V is even more available as it shows up in the used II lot a total of ten times (35, 59, 60, 63, 65, 78, 80, 93, 96, 100).
Now one could possibly suggest that there are "six unique black cars" if you include both the black 2001 Mazda RX-7 LM and black 2005 Ford GT prize cars, as these are unique in that they have no decals (actually the Mazda still has some of the decals, but not the GT4 decals). However, while the Mazda is truly unique as far as missing the GT4 decals, the 2005 Ford GT prize cars are all the same colors as the one you buy, but all are without the decals... so the black one is not so unique after all.
If you want to see pics of these as well as all the eleven FGT cars, and all the special and special colored cars, I made a gallery of them here: