| Car Clash | Audi R8 V10 Spyder vs. Porsche 911 Turbo Cabriolet |

Two drop-tops. One a supercar institution and the other an upstart that's caused more than a few ripples in the supercar hierarchy. The Porsche 911 Turbo Cabriolet is the benchmark, the car by which rapid convertibles are measured. Long a car that's been ridiculously easy to enjoy, its pace stupendous, its grip never ending. And its reign undisputed. At least until Porsche's distant cousin Audi rolled out the R8, and specifically the R8 V10 Spyder. Porsche no longer has the £110,000, open-topped, four-wheel drive, loony performance marketplace to itself. And by the evidence of our car clash here, Audi has caught Porsche napping.

Showroom appeal

Audi R8 V10 Spyder: Porsche 911 Turbo Cabriolet:

There's absolutely nothing wrong with the way the 911 Turbo Cabriolet looks. Until you park the Audi R8 Spyder alongside it. Do so and the 911's familiar, if more muscular and punctured, lines don't look quite so special. The Porsche demonstrates that with familiarly comes a degree of anonymity. The Turbo looks great, but it doesn't have us aching with desire. Blame all those same-silhouette Carrera 2 and 4s for robbing this big-money, big-power machine of some of its mojo.

That's the R8 effect, and it's particularly rampant when applied to the Spyder. We've always admired the R8, but never loved it. The Spyder is different. By losing its roof its desirability doubles, it looking and feeling so much more exotic. It makes the Porsche look positively austere, the detailing on the four-ringed machine so beautifully executed Audi could ask a good bit more money for it.

That's just on the outside. Get in and the Audi grenades the Porsche for showroom appeal. Every surface feels and looks like attention has been lavished on it, the 911 Turbo by comparison barely able to justify the £60,000 you'll pay for much the same interior in a standard Carrera. In this drop-top, forced-induction machine at twice the price it's just not good enough. The R8's interior drives that point home. And some.

Behind the wheel

Audi R8 V10 Spyder: Porsche 911 Turbo Cabriolet:

So what if the Audi is the looker? Porsche has always eclipsed its rivals on the road. Things don't sound great the first time I get behind the wheel of the Turbo though. It's quiet, too quiet; the mechanical symphony that is the R8's 518bhp V10 overshadows a muffled turbocharged 500bhp flat-six rumble from somewhere deep and low over my shoulder. Pull away and the 911's greater torque doesn't give it any more potency from standstill, though against the clock the Turbo betters the R8 Spyder to 62mph by 0.4 seconds. The blown 911 manages the benchmark in 3.7 seconds over the R8 V10's 4.1 secs, but on the road you'd be hard pushed to notice that gap.

The noise the R8 makes could convince you it's the faster of the pairing, the V10 sounding incredible from even the lowest of revs. The gearshift, an open-gated, six-speed manual, isn't quite as accurate or swift through its gate as the Porsche's slick stick, but it's more of an event with each ratio change signalled by a pronounced click-clack and a change in the V10's tempo.

In return, the Turbo's steering is the clearer, more precise of the pairing. There's plenty of confidence-increasing feel through the wheel's rim, the clarity of information fed to your hands greater than in the R8. It's marginal though, the Audi upstart proving to be tougher a foe than we expected.

The 911 feels the smaller, more pointy and precise car. The R8 feels larger and softer yet easier to enjoy. The Audi demands less from its driver yet arguably delivers more. The R8 Spyder is a car you can take out and enjoy immediately; the 911 Turbo is an easy drive too, but one that will challenge you to make the most of it when you ask for its ultimate performance. Whether you want that challenge or not is down to personal choice, but for all the huge appeal and incredible poise and pace of the Audi R8 V10 it's difficult to ignore the mesmerising ability of the Turbo on the right road. The Audi wouldn't be far behind at all.

Green guilt factor

Audi R8 V10 Spyder: Porsche 911 Turbo Cabriolet:

If you're burning over £110,000 on a sunshine supercar then it's unlikely you'll be too bothered about consumption and emissions, but for the record it's the Porsche that's the greener player in this battle. Drive it sensibly (some hope) and the 911 Turbo officially returns 24.1mpg on the combined cycle, while emitting 275g/km. For the extra 18bhp the Audi's V10 brings you pay with a combined fuel consumption of 19mpg and CO₂ emissions of 356g/km.

Money matters

Audi R8 V10 Spyder: Porsche 911 Turbo Cabriolet:

Choose either of these cabriolets and you'll be dropping a big pile of cash along with the roofs. You'll get no change from £112,000, and start hitting the options lists and you can add around ten grand to that. Of the pair the Audi feels like it's worth the outlay, the 911 less so - chiefly because you can have much the same shape and still good performance at a lower price point in the 911 range.

First past the post

Audi R8 V10 Spyder: Porsche 911 Turbo Cabriolet:

If the Porsche has taken a bit of kicking here then it's justified. That's not to detract from the Stuttgart machine; it's still an enormously competent and ludicrously fast car, but its shortcomings are brought sharply into focus by the more exotic R8 V10 Spyder. The Audi appeals on a different level. Its looks seduce, its soundtrack rouses and it's aesthetically and emotionally more appealing. You'll get out of the R8 buzzing.

The Porsche, while deeply impressive, is a bit cold in comparison. That's admittedly always been part of the 911 Turbo's appeal; the Porsche is still possibly the car we'd want as a daily driver - not least because it's more practical thanks to the extra space afforded by those rear 'seats'.

It's a tricky one to call in a first past the post manner, as for all their similarities these two cabriolets are very different. Perhaps it's a case for proportional representation then? Even then it's difficult to argue too hard in the 911's favour over the Audi. So the R8 gets the vote here. If you told us a few years back we'd be saying that we'd have laughed. Which only underlines how phenomenal Audi's achievement with the R8 Spyder is.