We are 25 miles west of Seville in Spain, where Renault is launching its new Mégane Coupé- Cabriolet (CC). A digital readout tells us the exterior temperature is 35C, so we pull over to raise the roof. Because, ironically, the sunblasted wastes of southwest Spain are about the last place you’d want to spend hours in a roofless coupé.

No sir, if you want to come to real convertible country, it’s right here in the good old UK. Which is why Renault hits us with two facts before setting us loose in the car. First, Britain is the largest market for convertible cars in Europe, and second, Britain “is damp and cold for most of the year”.

Which, according to the PR line, makes the Mégane CC the ideal convertible for these shores. The reasoning is that with its solid glass roof the Mégane CC is a light, bright place to be, even when the roof is fixed in place.

It’s true. With the roof raised — it scissors neatly into or out of the boot in no time — the cabin feels airy and spacious, unlike lots of fabric-roofed convertibles. And because you sit an inch lower than in the Mégane hatchback, the CC’s cabin feels secure and enveloping. It’s a nice place to be.

Even though the Mégane CC shares its platform with the hatchback, the only common bits of body are the grille, headlamps and bonnet. Everything else has been styled for the CC with the intention of giving it a sleeker, cleaner look than other hard-top convertibles such as the Peugeot 307 CC have achieved. From some angles the Mégane looks very elegant indeed. But from others it looks dumpy and bottom heavy, partly because of big overhangs at front and rear.

That’s the problem with this new breed of coupé cabriolet — the designers are handed a brief to “make it pretty, and also make sure we can fold a solid roof into the boot”. But even though the CC looks compromised from some angles, to my eyes it’s the best looking effort of its kind.

Renault also makes a lot of noise about the Mégane CC being a genuine four-person convertible. That is true, but only if they are very small or very uncomfortable.

The car will be offered with two petrol engines, a 115bhp 1.6 litre and 136bhp 2 litre. Unusually, there will also be a 120bhp direct-injection turbo diesel. Renault expects the diesel to be popular as a company car. It also says that a number of companies that vetoed cabriolets because of security and insurance are now happy to include the CC as being a coupé.

Just don’t come to the Mégane CC expecting a sports car experience. With all the structural stiffening to keep it from flexing with the roof down, plus the roof itself, which weighs 172lb, the CC is a heavy old thing. That’s revealed in the performance, which has the Mégane CC struggling on long inclines and less than eager to dispatch slower-moving traffic, even when you’ve got the more powerful petrol or diesel engine underfoot. We tried both and preferred the lazy flexibility of the diesel, which better suits the boulevardier character of the car.

Likewise, the Mégane’s handling is more suited to the streets of Monte Carlo than the Brenner Pass. The body tends to wallow through fast dips, and you get a fair amount of lean through tighter corners. The variable assist steering felt pendulous and offered little useful feedback.

It seems that Renault accepts that the CC could use a bit more poke — next year a turbocharged 165bhp 2 litre engine will find its way under the bonnet, possibly even a punchier 140bhp turbo diesel.

Priced from £16,500 for the entry level 1.6 litre model and up to £20,200 for the top of the range 2 litre version, the Mégane CC hopes to talk you out of alternatives such as the Peugeot 307 CC, not to mention rag-top competitors.

The Mégane CC is a pretty neat piece of work, and that glass folding roof really does the business. Accept that such a trick comes at the cost of performance and handling, and this might be just the car for our cold and damp land.

No wonder they’re putting the thing on sale in November . . .

VITAL STATISTICS

Model: Renault Mégane Coupé-Cabriolet 2.0 16V
Engine type: Four cylinders, 1998cc
Power/Torque: 136bhp @ 5500rpm / 141 lb ft @ 3750rpm
Transmission: Six-speed manual
Fuel/CO2: 34.4mpg (combined) / 196g/km
Acceleration: 0 to 62mph: 9.9sec
Top speed: 140mph
Price: £18,200
Verdict: The best looking sub-£20,000 folding hard-top, but performance and handling are compromised