It's almost hard to believe that the BMW-reimagined Mini is now in its 15th year. Call it a birthday, if you will, that the Cooper Convertible arrives this month in its third-generation and best-looking guise to date; a little puppy fat, cute looks, bags of adolescent vigour and tireless energy are embodied in this coming-of-age convertible.

Our quick take

The Mini Convertible is already the top selling convertible in the UK. And it's easy to see why in its third-generation guise: those quirky looks meet the mood swings of an adolescent when it comes to drive handling, cornering and comfort. It keeps you on your toes.

The lack of a touchscreen, the sometimes rigid ride, some irks with the gearstick, and the interface control positioning don't add-up to entirely matured perfection though. But then we're looking for more of a pool party, not a dinner party. And that's exactly what Mini gets right: the fun factor.

Mini Cooper Convertible (2016) first drive

Ahead of the official launch we got behind the wheel of both Cooper and pepped-up Cooper S Convertible models. Having blown out those imaginary birthday candles, we dropped the soft top, slotted the sunnies over face and, in attempting our best Brits-in-Portugal equivalent of Spring Break - hey a German manufacturer reimagined a British car, so we can think big too - to see whether this soft-top is a splash hit to drive.

Mini Cooper Convertible preview: Haven't you grown?

To paraphrase grandma: "my, haven't you grown?". Sitting in the Convertible is nothing like squeezing into the near-floor-level 1961 original Cooper. Indeed, this 2016 car is more spacious up front than older generations of Ford Fiesta. There's plenty of room for two, without legs knocking gearstick, or feet being contorted in the foot-wells.

But theoretically the Cooper Convertible isn't a car for just two people. The three-door hatch does actually have four seats, making it, well, a car all out on its own. Because you simply don't get other small four-seater soft-tops; the closest competition in our mind is the Fiat 500 or Mazda MX-5, which are different prospects.

We say theoretically too because, aside from working a treat for bag space, getting into the back might only be feasible for "mini people" (yes, we're going with that pun). Not that Mini hasn't made some progress here: the third-gen cars have 4cm more knee room than the second-gen models. Yep, a whole four centimetres; the kind of thing a budget airline might brag about, eh? Still, it's manageable space for the kids and more room is better than none.

Which isn't to scoff at the size difference, because the new Mini Cooper Convertible is the largest yet; it's 10cm longer than its predecessor. That's down to a new BMW platform, meaning a longer wheelbase - and even a larger boot, at 160-litres top-down (215-litres top-up).

Mini Cooper Convertible preview: The BMW influence

Over the years we've watched BMW's iDrive interface, on-board technology and media capabilities progress. This has obviously influenced in the Mini, which utilises an adapted iDrive controller to the centre console, positioned behind the gear stick. That means touchpad controls, and four main quick-access buttons for media, radio, navigation and telephone.

Now there's great potential in this system, but the actual controller is poorly positioned in the manual Cooper Convertible, the same for the S Convertible. It's a bit too much of a bend-the-wrist-back position, especially when toying with the back and option buttons. That's not so much the case in the automatic, which better places this controller thanks to more available space - making it much more comfortable to use.

As the centre LCD screen - which is surrounded by a light-up circular LED strip for some added Mini flare - is fairly sparse on control buttons, you'll need to be reaching to this lower iDrive-style control panel. As the centre screen surround isn't absent of buttons we often twirled the centre-positioned volume dial thinking it would cycle through options, when that's not the case.

But, and as with anything, the more you get used to it the easier it becomes to use. And we were soon toggling between navigation and phone-synced music via the Bluetooth connection. Shame the basic on-board sound system really isn't all that special - it does the job, but it's nothing to write home about.

Other top quirks include the red start-stop button to fire-up the engine, which has a fighter jet aesthetic, surrounding which are the as-standard air-con controls. We even had heated seats that, in the absence of super-hot sunshine, toasted our rears to near egg-cooking levels (best to go for the low rather than medium or high settings).

Mini Cooper Convertible preview: Topless fun

The whole point of a convertible is that it can be driven with the top down, taking in the open road, wind catching your face, messing up your hair. If you're contemplating buying a two-wheeled escape for your mid-life crisis then why not try a four-wheeled soft-top instead instead? We jest.

Opening up the fabric roof of the Cooper Convertible is a doddle: press-and-hold the silver roof switch, positioned top and centre in front of the rearview mirror, and it'll whip back the roof into its stowed position (if the boot is setup right, as with any soft-top) in 18-seconds. Which is an appropriate figure to keep in mind: because anything faster than 18mph and you won't be able to move the roof when on the go.

The motion of the top coming down happens in three stages, where it can "hang" a little between them if you don't keep your finger firmly pressed on the button. On-screen feedback will ensure you that everything is secure so it won't go flapping about like a broken sail as you scoot off down the road. The actual motion is nice and quiet too; we tested it a number of times and wouldn't fear doing so in the dead of night during a zombie apocalypse - it really won't attract unwanted attention.

But you'll need to keep your personal attention firmly fixed on the road. Although the third-gen Convertible has better visibility than its predecessor, it's still really not great visibility to the rear by any means, making motorway blind spots less than ideal. Even the A-pillars are chunky, so you may have to head-bob to keep them out of view around sharp corners. However, driving right-hand-drive cars on right-hand-drive roads likely enhanced this issue.

The saving grace to rear view comes in the form of parking, as every UK Mini Cooper Convertible will come with a rear parking camera as standard, which displays in real-time on the centre LCD display to aid you when in reverse. There are directional lines based on the position of the wheels and everything (just like any other typical rear parking camera; not quite as swanky as the newer 3D modelling systems found in Audi or BMW, for example).

Mini Cooper Convertible preview: Go-kart handling

Let's not spend too much time talking about going backwards, though, because - and like with any Mini we've driven - it's all about the go-kart-like fun of zipping around, front-facing (hopefully), and taking in your surroundings.

Under the hood we drove the 1.5-litre three-cylinder 134bhp Cooper Convertible, bettered by the 2.0-litre four-cylinder 189bhp Cooper S Convertible. The added growl and exhaust pops from the S add a smile to the face, but then it does cost more (base £18,475 for the Cooper, vs £22,430 for the S).

One shortcoming of the driving experience is a fairly long-throw gear stick. There's not the deft movement between, say, fourth and fifth from this 6-speed box. You'll be in and out of first gear in about half a second too, as second is the one that really gives the revs. The auto eradicated this problem obviously, but simultaneously extracted some of the fun that makes Mini, well, quintessentially Mini.

The Convertible is nippy, fun, cornering is a breeze - but it's certainly not always the most comfortable ride you'll ever have experienced. Maybe that was all the cobbled streets we encountered, or the slip-sliding on drain lids as we slunk around tight corners, but there's a rigidity to this Mini Convertible that you'll feel right up through the wheels. Good job the leather seats are comfy.

There are multiple driving modes too: Sport, which ups the throttle response aplenty, roars all the more when you fail to downshift properly, and spits aplenty in third gear; Mid, which, despite its un-Mini-like somewhat boring name, gives a more casual ride; and Green, which is all about economy, with less whizz bang than the other settings. Jostling between the three is actioned via a toggle wheel surrounding the gear stick - the kind of place where the hand falls naturally (unlike that iDrive-style controller).