IF Mazda’s new MX-5 Roadster Coupe had an extra 20bhp it would be close to perfect. Everything else about the car is great, except the performance.

As its name suggests, this latest addition to the MX-5 range goes from roadster to coupe thanks to a roof mechanism which does away with the car’s traditional canvas soft-top and replaces it with a two-piece item made of glass fibre and plastic composite.

Even though this roof and its electric motors add only 37kg to the MX-5’s kerb weight, the 2.0-litre engine simply hasn’t got enough power to make it a really sporty, adrenalin-rushing drive.

Which is strange, because on paper 160bhp pushing 1,200kg sounds promising, but it doesn’t deliver on the road. The engine feels strangled in all areas and needs a lot of revs to maintain momentum. With 180bhp this car would be much better.

At least it handles well thanks to a rear-wheel drive chassis and 50/50 weight distribution.

While performance may be disappointing, the roof is excellent. It folds away at the touch of a button in just 12 seconds and takes up exactly the same space between the seats and boot that the soft-top does.

It’s a clever piece of engineering and gives the MX-5 a more all-round appeal. With the roof up the cabin is snug and well insulated, with little wind noise, while roof down it has all the wind-in-the-hair fun of the standard MX-5.

The Roadster Coupe costs £1,200 more than the soft-top model, although it does feature climate control as standard – usually a £560 option, plus the £800 Option Pack which adds 16-inch alloy wheels, extra speakers and some leather trim for the wheel, gearknob and handbrake.

Mazda expects user-chooser interest in the car, which will take between 25-30% of the 9,000 MX-5s the firm sells in the UK annually. But much of this year’s allocation of a few hundred examples is already sold out through a pre-order website.

Adding a folding hard-top has instantly turned the MX-5 into a useable year-round car, and for a reasonable £1,200 premium.

And with that hardtop in place it will allay the fears of some fleet managers of offering a convertible car. It’s just a shame that, even in range-topping 2.0i form, it feels underpowered.

Max power (bhp/rpm): 160/6,700
Max torque (lb-ft/rpm): 139/5,000
Max speed (mph): 134
0-62mph (secs): 8.2
Fuel consumption (mpg): 36.7
CO2 emissions (g/km): 193
On sale: Now
Price (OTR): from £19,210