Judged on price alone, the changes to the Sport Classic don’t add up to double the price of a standard Carrera S. Some details – for example, the ducktail spoiler – will remain unique to the 250, but you could choose them as options on a standard Carrera S for less money. That’s of no consequence to collectors, though, who have snapped them all up regardless.

It's recognised by fans as one of the greatest sportscars ever – and with a rich heritage and bright future, it’s the model by which all rivals are judged.

But which 911 is Porsche’s favourite? And which car would the firm build itself if money was no object? The answer, until now, has been a mystery – but thanks to the first efforts of a new custom shop set up by the German car maker, things have become a little clearer.

This is the new Sport Classic, a 911 costing £140,000 which Porsche says demonstrates its best work. Inspired by the 1973 911 Carrera RS, it has been built by the newly formed Exclusive department.

It’s the RS-aping ducktail spoiler and Fuchs-style alloy wheels that really mark the Sport Classic out among 911s.

Only 250 of these specially painted, body-striped, double-bubble roofed models will be built, and if rumours are to be believed, they are already sold out. Given its astronomical list price, you might think it’s based on a Turbo, or shares its engine with the GT3.

But the Sport Classic is actually a heavily revised Carrera S. It’s a bit of a pick-and-mix model, with rear-wheel drive and bodywork from the wider 4S 911.

The engine has been boosted by 23bhp to produce 408bhp and the Porsche Active Suspension Management is uniquely set up, too. A Sports Exhaust system also features, and the Exclusive department has trimmed the interior in brown leather.

With the Sport Chrono Pack Plus as standard, PCCB (Porsche Ceramic Composite Brakes), a shortened throw manual gearshift and a 20mm lower ride height and limited slip differential, everything about the Sport Classic suggests a harder, more focused driving experience. It’s quicker from 0-62mph, with a time of 4.6 seconds, while the top speed is 187mph. However, the Sport Classic reveals a softer, more compliant set-up than the Carrera S on which it’s based. This, combined with the beautifully weighted steering wheel, results in a more composed 911 that makes the most of its additional performance.

The increase in torque is so tiny as to be insignificant on paper, but the Sport Classic’s 3.8-litre flat-six is more eager to pull from low and mid-range engine speeds. The sports exhaust accompanies the more muscular performance with a slightly more rousing note – if anything it could do with being louder. The manual gearbox swaps its cogs with the usual precision, while the ceramic composite brakes deliver huge stopping power.

There are a few other unique touches that only the most obsessive Porsche aficionados will notice too, like the RS door trims and the different material topping the gearlever. It’s all about the details, and there are plenty to take in with this unique Sport Classic 911.

Rival: Lambo LP550-2 Valentino Balboni
With a stripe, rear-wheel drive and limited to only 250 units, the Gallardo is a similar low- number model that will appeal to collectors. But it’s a harder-edged, faster machine than the 911 Sport Classic.