Audi R8 V10 Spyder £112,500

I approached the R8 Spyder as I'd approach my dream car. It's gorgeous, dramatic, and bonkers-fast. The roof folds for summer. The roof comes up again for winter, and Quattro drive hooks all that power onto a slippery road. Being an R8, it's both epic and ordinary in perfect combination. It's quiet when you need it to be, noisy when you want it to be. It handles commuting and motorways as well as mountain passes.

But it turns out it's useless. Not bad. Just useless.Which is strange because the original R8 coupe is one of the most useful supercars in history. You can have that coupe for thrills, and for every day. But there's one crucial detail that hobbles the Spyder as an everyday car. Where an R8 coupe has a handy space behind the seats, in the Spyder that space is used to store the folded roof. All that remains is the front boot, which, as with all R8s, is the size of a lunchbox.

So while the Spyder is on paper a relatively trifling eight per cent, or £8,690, more expensive than the coupe, in practice you'd also need to add the cost of forwarding your luggage. Say £28,250 for an S3, plus the wages of its driver.

Since as an R8 Spyder buyer you'll need to be so financially well-upholstered, you'll think nothing of forking out for two more cylinders. So Audi doesn't give you the choice and the Spyder is, for the time being at least, available only with the V10 and not the V8. And standard all-LED headlamps, magnetic ride, Bang and Olufsen hi-fi, and (nifty detail this) Bluetooth phone microphones embedded in the seatbelt fabric so that - even at big speed roof-down - you can phone your man in the S3 and tell him where to meet you with the fresh undies.

And what a time you'll be having en route to the rendezvous. We've already written thousands of words on the subject of our near-boundless love for the R8 V10. And now here's a convertible, with all the advantages that confers. A convertible is when you can't go very fast and want to enjoy the agreeable scenery and weather. A convertible is also more dramatic-looking. The absence of a roof makes a low and wide car even lower and, in consequence, wider-looking. And you hear that engine all the better.

Somewhere between a pair of TT RS straight-fives and a Formula One V10, it's a noise you just can't get enough of. There's heaps of torque too, delivered so nonchalantly that at first it's easy to miss how fast this car is. I kept shifting up at 6,000rpm. I had to remind myself to take it to 8,700. And in the region between those numbers, this thing is hectically, brutally fast. Oh yes, it's 100kg more than the coupe, so 0-62 takes just over four seconds rather than just under, but roof-down the Spyder's extra rush and noise makes it feel the more madly rapid.

The R-tronic single-clutch flappy-paddle gearbox is another £5,200. However much money you've got, I urge you not to tick that box. The manual is simply delicious, and doesn't make silly decisions. The R-tronic does - for instance, it changes down automatically as you approach a stop. Now imagine you decide it's time to go from third to second. If the moment you pull the paddle coincides with moment it decides to shift down anyway, your shift plus its shift combine to land you in first, and suddenly the car stands on its nose. Thunk.

All the R10's grip and traction are there. You can go at face-bending rates, and the R8 helps you out. But something here has been lost. The steeringremains progressive and confident, but a vital portion of the coupe's feedback and involvement has gone AWOL. It's sorely missed. The engineers say it's the extra weight that's to blame.

There was always a Spyder in the R8 plan. So I'm surprised by this marginal loss of finesse. I'm also surprised that the heater isn't more effective, and that the cockpit is actually pretty blustery at motorway speed - an MX-5 is far better in both respects.

So I came away from this drive feeling that the Spyder was a mild disappointment. Sorry. But then I'd set it such a high bar. I wanted it to be more special than the basic R8 V8 manual, and while it is in some ways, in others it's lost something. But you need to know two things to put that verdict in proper context. First I drove it on a day of relentlessly grey sky and cold wind. And secondly, I think that a basic R8 is already miraculously special.