Whenever there\'s talk of American classics at wheels towers, Imran enthusiastically pitches in. You\'d know by now that he\'s our in-house Yank tank expert, but with a minor flaw. All his opinions on American muscle invariably end up with a cheeky suggestion that the Pontiac Trans Am is the best collectible classic from the States. So when we saw news about American aftermarket retailer SLP Performance reviving the legendary Buick GNX nameplate with a tuned version of the current Regal, we were expecting another sermon from him on how the Trans Ams were better. But to our surprise, he didn\'t give one, and instead agreed with the rest of us that as far as American collectibles go, there\'s arguably nothing rarer than this 1987 gem. Anyone will, because not many cars have whipped up as much excitement and mad scrambles at dealerships in the US as the Grand National GNX did when it was announced. With General Motors\' G-body production set to end after the 1987 model year, turbocharged rear-wheel drive Buicks were all destined for a sad demise with it. But a few guys in the Buick team led by chief engineer Dave Sharpe and Mike Doble, Buick\'s manager of advanced concepts and specialty vehicles, were determined to send the Grand Nationals off with a bang. And what they had in mind as a swansong was a car on the lines of Buick\'s legendary GSX Stage 1. Instead of building it themselves, they handed the project over to McLaren Engines and Automobile Specialty Company, two big names in the American motorsports scene at the time. McLaren worked on the Grand National\'s intercooled and turbocharged 3.8-litre V6, which was already good for 245bhp and massaged it to squeeze out31 more horses. Doing the trick were a special Garrett T-3 turbocharger with ceramic turbine wheel and a larger intercooler, a recalibrated chip for the engine computer to allow up to 15 PSI of boost, and a larger dual exhaust system. Sending power to the rear wheels wasa modified four-speed automatic. To keep these extra horses grounded, the stock rear suspension was substituted with a ladder bar setup, and extended fenders housing special 16in black-mesh alloy wheels were added. The interior was also upgraded with special Stewart-Warner gauges. And it could be had in any colour, as long as it was black, and all exterior chrome bits from the standard Grand Nationals were deleted in the GNX, prompting many to call it a Darth Vader mobile. These mods added up to stunning performance figures of 0-100kph in 5.3 seconds and a quartermile in 13.3 seconds before topping out at 200kph, making it the fastest production car in GM\'s range (yes, even faster than a Corvette), and also one of the costliest in the US with a price tag of $29,000 (around Dh106,400). This, plus the fact that production was limited to just one year and 547 examples make it one of the rarest and most sought-after American classic cars. Although many of the GNXs that you\'ll find for sale are likely to have been thrashed by their original and subsequent owners, there are quite a few with surprisingly low mileage that show up once in a while on auction sites. But these obviously come at a premium, commanding prices in the range of $100,000. If you have that kind of money to spare and chance upon one in pristine condition, go ahead and snap it up, the value will only go up in the years to come. Also, with several dealers in the US and Canada specialising in parts for turbo Buicks, getting spare parts won\'t be much of a headache either.