Do you 'get' Smart? Do you think the original Smart car was a) an intelligent answer to the sludge of urban traffic or b) a silly motorised version of a child's Little Tikes car? Do you regard the Smart Roadster as a) a fantastically cool sports car for the Gatso generation or b) an expensively large Nike Air Max with a lawnmower motor in the heel?

If you answered 'b' to both those questions turn the page now, there's probably a picture of a Ferrari coming up soon. If you went for 'a' you probably 'get' Smart. In which case you should be very interested in the new Roadster Brabus. Annoyingly, this is not a showroom version of the barking V6-engined special that Brabus confected last year. The legendarily mental tuning firm may be famed for gallon-into-a-pint-pot engine transplants on regular Mercs but this Smart had to be built on the same line as the normal car, which meant ditching outsized motors in favour of stock mechanicals. But nor is this simply a smoke-and-mirrored-alloys rebadging exercise. Brabus is now to Smart what AMG is to Mercedes, creating spicy, head office-approved flagships but without going so bonkers that the results will panic the warranty department or have to be built in a special shed behind the factory.

Within those restrictions Brabus has done what it can to put some fire into the Roadster's belly, giving the revvy 698cc engine better breathing with a new intake and exhaust whilst reworking the turbo and ECU to allow an increase in boost pressure. The result is 24 per cent more power than the standard 80bhp Roadster. With 101bhp it's not a figure to make Horatio Pagani panic but it's okay in a car that weighs the same as your clothes.

And while it won't make you vomit with visceral acceleration, the Brabus Roadster brings a shot of extra vigour that works brilliantly in the real world. Think of it as a kick boxer: it looks small and wiry and it'd never win a straight fight with a muscle-bound SL55-style heavyweight, but its agility and hidden strength could allow it to deliver a quick kick to the knackers and then run off before the bruiser knows what has hit it.

To complement that feistier engine, the chassis gets lower springs, stiffer dampers and handsome 17in 'Monoblock' wheels, the net result of which is that the Brabus feels better tied-down and less crashy. In fact, why wasn't the standard car like this from the off? The prevailing condition is still lashings of grip giving way to gentle understeer and, although the extra power allows a wag of the tail, it's briskly snuffed by the ESP you forgot to switch off at the start of the journey.

Which is where we reach a problem with how much you 'get' Smart. Hairy-arsed sports car drivers will dismiss the Roadster as a waste of time because you can't circumnavigate every roundabout sideways. The more cerebral will appreciate that even Stig Blomqvist doesn't drive to the office on permanent opposite lock, in which case the Smart's ability to cover ground at decent speeds without killing you or dropping below 40mpg is something to celebrate.

Then there's the semi-manual gearbox, here with standard paddle shifters. 'Serious' drivers don't like these, just as their fathers got all huffy when some bounder invented the automatic choke. And they'll be pleased to know that, despite clutch and ECU tweaks which make it feel faster than standard, the Brabus Roadster's shift isn't as good as the best manual changes. But learn how to drive it, how to feather the throttle for up-changes, and it's not the unworkable pain in the underpants you might have thought.

No, the gearbox is not the problem it's made out to be. The steering, on the other hand, could be quicker and the brakes feel mushy, although they're actually very strong and showed no sign of wilting after a demanding mountain descent. More disappointingly, the brilliant wastegate pssssh that marks aggressive upshifts in the stock Roadster has been reduced to a timid sniff in the Brabus. This is a huge shame because it was one of the things that added to the car's character.

And character is really what this car is about. If you don't appreciate that you'll see it as an expensive irrelevance. If you are in tune with the Roadster's charms you'll relish its feisty engine, its growly soundtrack, the view over the swooping wings from that low-slung driving position. And you might even be prepared to swallow the distressingly hefty ΂£17K/΂£18K price tag for the Brabus version's extra power and usefully improved chassis because it's a unique little funster. If you can stomach paying more than MR2 money for a 700cc car, then you truly 'get' Smart. In which case this is the Smart to get.