bradley emmanuel

We Brits are an optimistic bunch. Even though we only get about 38 minutes of sunshine each summer, we buy more convertibles than almost anyone else in Europe. Britain is the second biggest European market for drop-tops and that means we have a greater appetite for open-air motoring than the French, the Italians or the Spanish.
The only problem is that removing the roof can spoil a good car, or at least make it noisier, sloppier to drive and easier to steal. That's why car makers invented the metal folding hard top, which is meant to mix the advantages of a coupé with the fun of a cabriolet.

This arrangement features on the latest Lexus IS 250C, a £34,550-plus open-top version of the IS saloon that's pitched as a rival to the class-leading BMW 3-series Convertible and recently launched Mercedes E-class Coupé. The IS 250C is claimed to have the world's fastest metal folding roof. Like most rivals' similar systems, it is split into three sections to ease stowage. Powered by 15 electric motors and fitted with 37 sensors to ensure its panels don't thwack anything when, at the touch of a button, they flail into the air and fold intricately into the boot, the intricate system even has a "roof brake" to allow a well-damped closure.

To accommodate the intriguing folding roof system, Lexus has redesigned much of the IS's bodywork. Only the mirrors, door handles and bonnet are common between the four-door saloon and this convertible, so the two look quite different. To my eyes the IS 250C is a little frumpy and inelegant, despite the designer's best efforts to disguise its elongated rear end – an Audi A5 Cabriolet is much prettier.

An A5 isn't as refined, however. Lexus has paid special attention to this area, adding extra sound-deadening materials in an effort to make the IS 250C impressively quiet. But when the roof is down these gains don't count for much and this soundproofing also makes the car considerably heavier.

At least the ride is smooth on standard 17in wheels as we pootle along Nice's coastal promenade – the sort of glamorous setting this car has been designed to suit. The upmarket cabin is also as well-appointed as an MP's second home, if a little more compact, while the generous boot is big enough for two large travel bags.

Halting at a traffic light provides the opportunity to put the speed of this roof to the test. Press the button and all 15 motors buzz into life. A driver behind beeps his horn, assuming we're going to hold him up, but just 21 seconds later the process is complete.

We head out of Nice and up to the twisty roads that form stages of the Monte Carlo Rally. This is where the IS 250C's flaws are most cruelly exposed. The only engine on offer – a smooth-revving, 2.5-litre V6 petrol engine with 205bhp – feels weak and overwhelmed in this environment, while the automatic gearbox swaps cogs constantly in an effort to find more urge. The United States will get a version with an extra 100bhp but the bigger engine's emissions preclude its appearance in Europe.

Much as the engine won't satisfy keener drivers, neither will the handling. The problem is the car's bloated weight, which prevents the IS 250C from having the panache of cheaper rivals such as the BMW
3-series Convertible. It's safe and has numerous electronic driver aids, but it's not sharp. It's disappointingly dull.

All in, this is a refined cruiser that could appeal if you're after a plush, comfortable and soft-driving convertible. But the reason we buy so many open-top cars in Britain is surely because they're fun, and the IS 250C's sanitised driving sensations mean that it isn't.