In a word? Brilliant. The 911 Coupe sets the benchmark in this class for driver thrills, with amazingly precise steering and stable yet involving handling. And the Cabriolet feels the same, but it's even more fun because if you drop the roof – which takes just 13 seconds and can be done at speeds of up to 35mph – you can hear every note of the amazing flat six-cylinder engine. The standard Carrera can do 0-62mph in 4.6 seconds and 176mph and will have more than enough performance for most drivers, but the S has even more punch and can do 0-62mph in just 4.3 seconds and 185mph. Both those sets of figures are for the PDK automatic, which shifts even faster than the seven-speed manual, although it has an annoying tendency to kick down sometimes even in ‘manual’ mode.

The 911 has always been the world's most useable supercar, combining great visibility with a relatively small size and lots of easy to access performance – the Cabriolet continues that theme. It's certainly as quiet as the Coupe with the roof in place, while roof-down you can raise the wind deflector to reduce buffeting.  It's still a noisy place to be – it's difficult to hold a conversation on the motorway roof-down – but the pay-off is you can hear even more of the rear-mounted engine. With a longer wheelbase, there's more room inside the cabin, and the driving position is easily adjustable and very comfortable. The sports seats are firm and supportive too. The ride is pretty good, especially given the grip available, and you can stiffen it up by pressing a button on the centre console.

Build quality is beyond reproach – from the way all of the controls have an expensive-feeling oiled precision, to the chunky switchgear and beautifully stitched leathers on the seats.  You certainly feel like you’re sitting in an £80,000 car. Porsche has an enviable reputation for producing enormously fast sports cars that don’t seam to suffer from mechanical or electronic gremlins either – and we’d expect the 911 Cabriolet to carry on this tradition.

With a deep boot at the front, you’ll be surprised at just how practical the 911 is. The Cabriolet has exactly the same amount of space as the Coupe, with enough room in the front for a medium-sized suitcase and several squashy bags. The back seats are so small that only the tiniest of children will be able to fit – but they’re not really for sitting on anyway and should be treated as an extra stowage shelf, for coats and bags. Being about as wide as an Audi TTand only slightly longer, the 911 is easy to park and place on the road too.

As standard you get the electric roof, climate control, a 4.8-inch colour screen on the dashboard, leather sports seats and 18-inch alloy wheels – an okay amount of equipment if not particularly generous, especially given the price tag. Options include BOSE and Burmester surround sound systems, a seven-inch touchscreen a wide variety of alloy wheel designs. If you want the open-top flat six-cylinder engined Porsche experience but don’t have £80,000 to spend on a new car, you could always buy a Boxster – which is brilliant in every way and costs around £40,000 less.

The new 911 Cabriolet is much more efficient than before, with the PDK-equipped Carrera claiming 33mpg and just 198g/km of CO2, thanks partly to a standard stop-start system. It should also hang onto its value too – 911s are always in demand on the second hand market. But while you’ll be able to get 30mpg on the motorway if you’re gentle with the accelerator, insurance, tyres and servicing will be very steep indeed, although no worse than a similarly priced Audi R8 Spyder.