But once you've got over the modified looks, the Roadster - its commercial viability for the UK currently under consideration - offers quite a chunk of performance for not a lot of cash, an endearing characteristic that it shares with its tin-top sibling.

Structurally, the 350Z Roadster differs from the coupe with extensive reinforcements that stiffen the floor, windscreen and sills. The result is a structure from which only the worst roads will elicit a brief shudder. The downside to all the gusseting is a weight gain of 127kg, although acceleration numbers suffer only slightly compared with the coupe: just two-tenths of a second are added to the 0-60mph time.

Dropping the top is a one-touch, 20sec affair. Stop the car, hit the button and after the whirring of solenoids and electric motors subsides, your headroom becomes limitless. The top stows neatly behind the two roll-hoops and under an elegant tonneau and is fully lined, weatherproof, and quiet. With the top in place, the Roadster retains the interior space of the coupe. Boot space is essentially unaffected by the conversion to convertible, and provides ample room for two people's gear.

The sound that comes into the cabin is the same melodic exhaust note produced by the coupe but, with less tin and glass between you and the two fat tailpipes, its effect is amplified. The Roadster uses the same 3.5-litre V6 as the coupe. What makes the Roadster an engaging partner on a country road is the relaxed nature of the engine. The V6 has variable valve timing giving it excellent flexibility, so changing gears is an entertaining diversion rather than a necessity. More highly-strung roadsters, like the Honda S2000, require you to be vigilant to keep the power on tap; that's not the Z's way.

The Roadster's handling gives away little to the coupe's, with the gain in weight hardly being felt on the track. It does have 'issues', however; the brakes get spongier sooner in the Roaster and it shares the coupe's tendency to understeer. What is nice about the understeer, however, is that if you're prepared to abuse the front tyres, you can enter corners at a pace that would frighten you in an S2000. Around slower corners the torque-rich engine easily overwhelms the rear tyres to provide delightfully dramatic oversteer.

Off the track, at less than ten-tenths, the massive grip from the Bridgestone Potenzas is rarely challenged. The public road persona of the Roadster ends up being satisfying and confident, requiring minimal effort for maximum pleasure.

With the top down, passers-by will notice the Roadster's show-car interior style. Look closer, though, and they (and you) will spot plastics that seem to have been chosen on price rather than their longevity or appearance. Odd bits of trim suffer a transitory buzz when you run the engine through its higher register.

The cloth seats in our test Roadster were great on and off the track, being supportive in all the important areas for motorway runs and properly bolstered for high-g manoeuvres. The seating position in the Roadster is sunken, with the top of the doors at shoulder height, so you feel like you're sitting on the floor. That sinking feeling is compounded when the top is raised. Being this low does have an advantage, though, because even at high speeds the wind flows over your head without re-entering the cabin from the rear. Men with toupees, trolling for floozies, will be impressed.

Although the Roadster doesn't cede much performance to the coupe, the characters of the two models are entirely different. The coupe is more of a pure, no-nonsense sports car, for the hardcore brigade. The Roadster, on the other hand, is a bit of a boulevardier, as much for show as go. But the ragtop is immensely capable all the same, and on a hot summer's night its allure would be very hard to resist.