Renault Mégane Coupé-Cabriolet

A key attribute of any open-top car must be style.

That style may be a celebration of engineering purity and aesthetic rigour, or it may be a paean to elegant flamboyance. So it follows that unless you have bought an open car purely for your own driving amusement, how it looks is important because you will surely be looked at.

Some people think the new Renault Mégane Coupé-Cabriolet, pictured here, is a good-looking car. Eye of the beholder and all that, but the undeniable visual drama and dynamism of the popular Mégane Coupé seems to have evaporated here. The problem, of course, is that coupé-cabriolet business which too often imposes a bloated bottom on a design which, given its style-heavy role, could really do without the excess fat. The good points of a coupé-cabriolet (CC) are the resistance to vandalism, the longevity of the roof and the likelihood of hood-up travel as quiet as that of a car with a permanently fixed roof. Against them are the looks, the considerable weight of the folding roof and its mechanism, and a boot space dramatically cut when the folded roof is occupying it. These negatives aren't exclusive to the Mégane, of course; they apply to nearly every four-seater coupé-cabriolet.

So what's new here? The previous model, launched in 2003, was the first CC to have a glass roof panel, and this one reprises the idea with a 10 per cent bigger glass area. Inevitably this new CC is bigger and heavier than the previous one. Length increases by 125mm or 5in, weight by a worrying 180kg – to make this ostensibly compact cabriolet a one-and-a-half-tonne car. The wheels are a hefty 17in in diameter. Despite this ample mass, the cheapest version comes with an engine of a mere 1.4 litres which sounds woefully under-specified until you realise it's a turbocharged unit with a healthy 130bhp and a healthier 140lb/ft of torque. Other engines include two 2.0-litre petrol units, one of 140bhp linked to a CVT automatic transmission, one of 180bhp for a GT-badged CC, and three turbodiesels of 1.4, 1.9 and – for a GT again – 2.0 litres.

The £21,595 test car's little 1.4-litre engine is unexpectedly impressive. It's unusually smooth and quiet, it pulls with vigour across a broad speed range and without the delay in response sometimes felt in small-capacity turbo engines, and while far from truly rapid the Mégane cruises easily and overtakes confidently.

Roof-up, this is a very quiet car. Roof-down, too, it's a relaxing drive with not much buffeting from the wind especially if you fit the optional wind-blocker across the back of the cockpit. Then, of course, you can't carry rear passengers who would otherwise find more space than is usual in a CC. It's a viable four-seater, helped by that extra length.

Opening or closing the roof takes 23 seconds. Inevitably the steering loses some sharpness with the roof open, but its responses are progressive and the weighting is just right. For the most part this Mégane copes well with our undulating roads, too, but certain big bumps upset it badly. The resultant thump and shudder can even be enough to dislodge the roof's position if it is shut, even though this new CC's bodyshell is said to be 30 per cent more resistant to twisting.

You can probably tell that I'm a touch underwhelmed. It's competent enough, but it lacks the sense of fun and pleasure that a convertible should offer. An excess of technology further gets in the way of the relationship – such as the electric parking brake which severs an important car-driver interface, and an intensely annoying warning shriek should you dare open the driver's door with the brake off. Sometimes you have to do this just to see when parking, and I'd rather not be admonished. I don't often swear at a car, but I did then. And you shouldn't have to do that to a pleasure machine.

The Rivals

Audi A3 Cabrio 1.2 TFSI: from £20,295.

Fulfils the style brief beautifully while being admirably compact. A soft top and a good drive.

Peugeot 308 CC 1.6 VTi: from £20,595.

From a similar mould to the Mégane but more stylish and more fun to drive. Still no sports car, though.

Volkswagen Eos 1.4 TSI 122: from £20,695.

One of the better-looking CCs, and it has a glass roof like the Mégane. Little driving excitement here.