The 1980s will be remembered for the liftback coupe, a bodystyle that, aside from the Nissan 370Z and a few other isolated cases, is mostly nonexistent today. In all likelihood, the late 2000s and early 2010s will be remembered in 20 years time by a spate of bizarre lifted four-door 'coupes' that popped onto the market.Much like those liftback coupes, most of which were eventually replaced by traditional trunks, it doesn't appear vehicles like the Acura ZDX and Honda Crosstour are long for this world (the exception being the BMW X6 , which will almost certainly see a second generation or at least a significant refresh). Sales of five of the six four-door coupe-crossovers on the market had a year-over-year drop in September of anywhere from 39 to 80 percent, according to a new report from Automotive News . The Infiniti FX/QX70 BMW X6 and 5 Series GT all saw drops, while the ZDX saw its sales drop even further, making it about as popular as Congress these days.This news wouldn't be tough to swallow were the rest of the industry down as well. But with sales of traditional luxury crossovers up ten percent so far in 2013 and the overall crossover segment up 15 percent overall, the losses by the four-door CCs is rather glaring.Part of the reason for the sales drop is likely due to simple human nature – these are fashion-forward vehicles that make a statement. The result is that the people who are truly interested in them buy them early and are quick to move on to the next big thing, giving these models a very brief shelf life, not unlike sportscars and most convertibles. That said, there's no shortage of more practical issues that limited their broader appeal. Besides the additional price of entry demanded by the coupes, their lack of rear headroom, limited visibility and diminished utility have arguably made them a tough sell with consumers, particularly when they're forced to share showroom space with more conventional platform-mates.