I just know that they were highly successful sports coupes in the racing circuit even after they had essentially been outdated.
At least in Britain (the source I have is a British one) the coupes did not sell well because they were very expensive to import into the country and many people did not like the stripped-down car they got for the price. The alloy panels on the car, though light, were easily damaged and expensive to replace, the seats were much lighter and thinner and were rather uncomfortable, and the interior in general was quite sparse.
But hey, this is a performance car, and that shouldn't really be too important. I remember that the earlier models simply had the 3.0 inline six that was in the 3.0 CSi models, but later models had that upgraded to a 3.2 litre engine. Later models also had little aerodynamic bits (they were dubbed "Batmobiles") that apparently helped more than one would think. Plus, they really don't look silly when compared to modern body kits and spoilers.
My question - where are you finding one of these? I don't think they were ever sold in the United States, and not too many of them were made. If it's a good price and you have the money to maintain it well then I say go for it.
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Member of the "I haven't passed a cop at 115 mph or drifted on a neighborhood street to impress a girl because I'm not a fucking idiot" club