In case you've been on Mars for the last year, 2011 saw the 50th anniversary of the Jaguar E-type, writes John Simister. The open version is probably Jaguar's most-admired roadster, but the car you see here bears another superlative to make this a doubly significant year for topless Jaguars. With its top speed of 186mph and a 0-62mph time of 4.4 seconds, this is the fastest open road-going Jaguar there has ever been.

Creating it wasn't especially difficult, however. Six months ago, Jaguar brought us the XKR-S in coupé form, with 550 supercharged bhp instead of the regular XKR's 510 and a torque increase to match. Remapping of the electronics and a freer-flowing exhaust system did the trick, with stiffer springs (by 30 per cent) and suitably recalibrated dampers now deprived of their actively-variable settings providing the suspension sinews to match.

Wider wheels, forged for lightness, complete the mechanical modifications, while the body gets a new nose with slots ahead of the bonnet, a carbonfibre splitter and side ducts which channel air along flared-out sills. Carbonfibre forms the new rear wing and lower valance too, all designed for extra stability and reduced lift at high speeds.

So coupé and convertible are the same, even down to the suspension calibration, apart from the obvious roof difference. This says a lot for the stiffness of the XK's aluminium structure, which was designed as a convertible from the start. The open car's advantage, though, is that with the roof down its occupants are especially well placed to hear the outpourings of the 'Performance Active' exhaust system.

Which is exactly what I did in the city streets around the Los Angeles Auto Show buildings. The car I drove was not bright white and show-perfect like the example in the glossy press pictures here, but the well-exercised test mule, painted in satin black, that has been pounding the Nürburgring's Nordschleife for pre-launch testing. With racing seats and an impregnable roll cage, it was one of the more claustrophobic open cars I've driven.

But I drove it sufficiently far, and with enough exploration of engine revs, to discover that it soaks up Los Angeles road bumps with surprising suppleness and no trace of shudder. And that it sounds fantastic, its exhaust emitting a staccato, machine-gun, sizzling-V8 crackle as you snap the throttles open and hold them there as long as you dare – which in my case was until I saw the LAPD patrol car under the bridge.

It was just a taster, but this is one rapid, highly-toned Jaguar which is perfect for hunting down Mercedes SLSs and Ferrari 458s. It's a proper sports car, albeit a large one and quite expensive at £103,000. The combination of this development car's hopeless view out past the roll cage and a phone-focused woman failing to look before stepping off the sidewalk was not a good one, though. Fortunately we all survived unscathed.

Text: John Simister

Photos: Jaguar