Instead of lamenting the paucity of true grunt, you marvel at how much performance turbocharging can squeeze from just 600cc and three cylinders. If you're in the right frame of mind - Mozart rather than Beethoven on the stereo - even the slightly ponderous shifts of the clutchless, six-speed sequential gearbox can be a source of fascination instead of frustration. To cap it all, if Noddy drove a 911, its engine would sound like a Smart's.

As regular readers will know, we rather like that. The Smart, admittedly regarded as a toy by some, is more than niche, it's 'thinking different' in a way that Apple Computers would be proud of. But we're here in Portugal to witness Smart's 'difficult second release'. In fact, 'difficult' hardly covers it. Having successfully convinced at least part of the world that it doesn't need a sports car to have fun on four wheels, it's obvious what you build next...

Even more curiously, Smart's marketing thrust for its new mid-engined Roadster and Coupe - same car, different roof treatments - is nostalgia. The world's newest and smallest-engined sports car, the thinking goes, will evoke fond memories of crusty ancients like the Frogeye Sprite, Spitfire, Midget and MGA, classic British roadsters that were basic and not all that quick but uncomplicated, honest fun.

Quite clearly, these Germans are having a laugh. What memories? Sprite's a fizzy drink, Spitfire's beer and frog eyes are what Kermit has. The deliriously funky new Smart twins (Fisher-Price goes acid house) are transparently youth magnets - My First Elise/Exige for those in frustrating early-twenties limbo. They should be regarded as the automotive equivalent of training combat jets: safely sub-sonic but packing authentic visual, aural, dynamic and tactile cues; simple, affordable conduits for high-octane fantasies.

So what matters is not some wistful spiritual heritage but price and insurance group. For the basic Roadster driven here the figures are ΂£13,495 and 8. Maybe not as low as some were hoping for, but Smart is planning to bring over 100 down-specced, City Coupe-engined left-hookers (60bhp, steel wheels) for ΂£9995 to underpin the ultra-affordable roadster promise. And for those who just can't wait until September, lhd versions of the pukka 79bhp Roadster and Coupe, at ΂£12,495, will be in showrooms for the summer.

The new Roadster, like the Coupe, is 35 per cent City Coupe: common parts including driveline, suspension, seats, heating and electrics, and they work well. But the other 65 per cent looks frankly wonderful. Exterior styling is amazingly low-slung and sexy for something so small. Wide of track and with a wheelbase 548mm longer than the City Coupe's, the exposed structural steel accent melds perfectly with the Targa-style roof design, the neatest aspect of which is the fabric top that unfurls out of a space behind the seats on detachable side rails (powered operation optional, but so cool you won't think twice).

The rails stow neatly in the front boot and the two-piece solid roof panels (if you order them) in the rear boot which, being roughly the size of an oven baking tray, leaves precious little room for anything else. If the need to carry luggage is likely to be an issue, the Coupe is a much better bet.

On the move with the windows down and all roof parts removed, the Roadster feels breezy in every sense. Not least its performance - and the huge character that comes with it. Smart's sweet-spinning jewel of a three-pot motor has been eased out to 698cc, turbo boost rounded up to a neat 1.0bar and the exhaust manifold enlarged, while a forged (instead of cast) crank, new pistons and alloy turbo-housing cope with the extra internal heat and energy. And since the Roadster weighs just 790kg (200kg less than the City Coupe) power/weight is a respectable 100bhp/ton, or about the same as a CitroΫn Saxo VTR. Smart's 10.9sec
0-62mph claim if anything feels a little pessimistic, despite the still somewhat leisurely shift-speed of the sequential gearbox - now available, amusingly, with steering wheel paddles.

But to regard that as a niggle would be wrong. Likewise the rather slow-witted responses of the otherwise quite feelful unassisted steering (power optional). These are as much part of Smart DNA as the clever plastic/steel frame construction, dials on stalks and feel-good fuel consumption (55.4mpg combined, by the way).

What's changed is the context. The bits that provide diversionary fun in the City Coupe - 911-soundalike motor, fluttering turbo wastegate, six-speed sequential box - are far less quirky and incongruous in the Roadster and all the more satisfying as a result. And because the grippy, astoundingly supple-riding and endlessly forgiving chassis conserves the available speed so well, the little sports car is actually decently quick point-to-point.

If, it has to be said, a little two-dimensional. The standard ESP is surprisingly unobtrusive but there simply isn't enough grunt to do much about the nose-led balance in the dry. The Roadster corners quickly and with terrific damping control but very little steering/throttle ballet. So you start thinking very un-Smart (stupid?) thoughts. Like 'why not 100bhp?'. Because you might as well have 110bhp in a Mazda MX-5 for ΂£1500 more.

The Smart Roadster is toy-like and playful and desirable. TVR can rest easy, but it does what it does brilliantly.