FOUR-SEAT convertibles are more prone to torsional stiffness deficits than two-seat convertibles, so it would be reasonable to expect the new Mini Cabrio to feel quite a bit looser than its hardtop sibling.

Not so. There may be a bit of squeaking from various points where the soft-top meets the window frames, but the Mini Cabrio generally feels surprisingly taut, especially when you remember that the open spaces extend for something like three-quarters of the total body length.

It’s possible to think of a number of prestige soft-tops in the past that have felt a lot less solid than the Mini.

Some of this has to do with the softening-up of the suspension – a common ploy with convertible versions of hardtops - which minimises the harshness, and signs of flexing, at the expense of a little handling response.

The base Cooper Cabrio suspension is a little cushier than the hardtop, while the Cooper S gets less aggressive "sports" suspension in place of the hardtop’s "sports-plus" set-up.

The bottom line though is that the Mini Cabrio retains the go-kart feel that is central to the marque’s essence.

It is heavier, by 100kg, and this slightly blunts the 1.6-litre engine’s performance. Not so much a worry in the supercharged, 125kW Cooper S, but introducing signs of bottom-end reluctance in the 85kW Cooper – although it works quite well once revs are piled on.

Fortunately both sound the part – a willing, omnipresent note in the Cooper and a supercharged whine in the Cooper S when it’s being worked.

Both sound even better with the roof lowered - which brings us to the very clever soft-top design that incorporates a sunroof and a sort of mini-hatchback into the usual convertible configuration.

Lowering or raising the roof is fully automatic. The first phase of the lowering process introduces the Mercedes A-class style sunroof mode and can be actuated at any speed.

The second phase needs to be conducted at a standstill and sees the upper roof rails folding back and accompanying the roof as it moves rearward behind the fixed rollbars.

The process, Mini says, takes about 15 seconds - pretty quick for what is actually quite a large convertible roof.

The hatchback function is a little convoluted and tricky to master, but it beats any other convertible we can think of for practicality.

As well as allowing a larger opening for luggage – the boot is bottom-hinged, like the original Mini, and the below-window section of the roof hinges upward – the split-fold rear seat provides a genuinely useful, up to 605-litre load area. And the rear window is glass, with demister imprints.

Apart from a feeling of being more closed-in when the roof is up, the general driving experience is nicely retained.

The S version’s six-speed transmission shifts with precision through a nice, tightly-spaced set of ratios – the base Cooper’s five-speed is equally as slick but without the close-set gear spacings.

The barely detectable evidence of any extra body flex – there’s no sign of scuttle shake - means the car feels reassuringly solid, and the steering is just as sharp as in the hardtop.

The turning circle is pretty big though and the supercharged S engine is strong enough to induce noticeable torque steer.

The 154kW Works version, which has just been upgraded and is available in the Cabrio as well as the hardtop, fights the steering wheel even more, either when exiting a corner in a low gear or accelerating madly through the ratios.

With the roof down, and without the optional wind-blocker that fits between the rear rollover bars, there’s minimal blustering in the cabin, along with very little disturbance of the coiffure.

General road noise is noticeable but not disturbingly so and wind noise, roof up, is not bad for a convertible.

The Cabrio seats are the same as the hardtop too, which is good and bad – good because they offer pretty decent support, bad because the (manual) adjustment mechanisms remain as fiddly as ever.

The control for flipping the seat forward, then back, to allow access to the rear seat is confusing and can result in the just-entering rear seat passenger getting a decent smite on the shins as the front seat moves back into place.

The instrument panel is the same outrageous arrangement as the hard-top Minis, with a central tacho big enough for a Kenworth on the Cooper and a two-dial arrangement containing tacho and speedo directly ahead of the driver on the Cooper S. The visuals inside are just as entertaining as those outside.

A $6400 surcharge for the Cabrio seems reasonable enough, especially when you consider the hardtop prices were dropped recently. This means the Mini Cooper Cabrio, at $35,900, is only $3250 more expensive than the hardtop version was at launch.