FORGET everything you know about Maserati convertibles because the boutique Italian brand finally has a drop-dead gorgeous new drop-top that invites no comparisons with the dynamically and ergonomically flawed two-seater Spyders of old.

The craftily named, GranTurismo coupe-based GranCabrio not only represents Maserati’s first fully fledged four-seater convertible, but is also the brand’s first no-strings-attached rival for established top-shelf cabrios such as the Mercedes-Benz SL, Porsche 911 Cabriolet and Aston Martin DB89 Volante.

At a relative snip more than the 5.5-litre V8 SL500 and BMW’s 5.0-litre V10-engined M6 Convertible, however, the $338,000 GranCabrio costs only about $20,000 more than the GranTurismo S coupe and will be even more exclusive.

Scarcity and its undoubtable Pininfarina style, presence and unashamed flamboyance will be key selling points for the GranCabrio, but prospective customers will also be glad to learn the talented GranTurismo has also injected a big enough dose of competence to relegate any lingering memories of the Spyder to one’s rearmost lobe.

A day-long drive over some of the most punishing, ill-maintained rural roads in the trendy but long neglected Byron Shire of northern NSW this week proved the GranCabrio has the substance to match its style.

Maserati really appears to have done its homework with the GranCabrio, which piles on a relatively paltry 100kg in kerb weight over the GranTurismo upon which it’s based – 65kg of which goes into a fully automatic five-arm, three-layer soft-top rather than a fancier folding hard-top design like the one on Ferrari’s more expensive California.

While the roof offers a whisper-quiet opening/closing time of just 20 seconds, it can also be operated at up to 30km/h but takes a little longer at 28 seconds. With all four windows up, wind noise and buffeting in the cabin is low enough at all but illegal speeds to render useless the expensive optional wind-blocker, which makes the rear seats redundant too.

The rest of the GranCabrio’s weight gain goes into cabrio-specific developments like unique audio and climate control systems that automatically adjust according to cabin noise levels, seat-mounted side/thorax airbags, well concealed pop-up rollover hoops mounted behind the rear head restraints and a comprehensive chassis strengthening program that adds substantial rigidity to the A-pillars, rear bulkhead and floorpan.

It works, too, because despite a surprisingly firm suspension tune that some potential buyers may find just a little edgy – especially in Sport mode – the GranCabrio feels almost flex-free, with only minor A-pillar and steering column shudder noticeable over extra-harsh surfaces.

No, it’s not as stiff as an SL or 911 Cab, but the well-sorted GranCabrio chassis is good enough to make the old Spyder feel positively liquorice-like, and to forget you’re driving the longest-wheelbase convertible in its class – and sometimes even that you’re not driving the GranTursmo itself.

The rangy wheelbase liberates more rear legroom than any convertible available, including the Bentley Continental GTC, making the deeply bucketed twin rear seats as commodious as the front pews – at least with the roof down.

Unfortunately, the generous rear legroom is not matched by headroom, which is tight, but the GranCabrio compensates somewhat for this with twin rear cup-holders, effective rear climate-control outlets, a large centre console and twin outboard armrests – all lavishly lined in leather.

Maserati’s third model line, then, is far from perfect – no Italian car ever has been – and further foibles can be found in the thick and cosseting A-pillars, the ever-present reflections from the large central information screen with the roof down and the lack of 10km/h speedo numeral increments (including the all-important 100km/h mark).

Oh, and while we’re complaining, the fixed-size boot is of course tiny and there’s an absence of top-end features found in similarly expensive rivals, such as soft-close doors, keyless starting and radar cruise control.

But the GranCabrio is not a triumph of style over substance and delivers the things that matter most to buyers at this level.

Sure, one of the most memorable attributes of the long-forgotten Spyder was its glorious V8 engine note, but the GranCabrio improves on it in this area too.

Apart from delivering brute force at speeds of up to 7500rpm, the charismatic Ferrari-built 4.7-litre bent eight plays an intoxicating tune at any speed, but when modulated via the Sport button or large column-mounted gearshift paddles it’s enough to make any Italian sportscar lover go weak at the knees.

No wonder Maserati’s all-new convertible is not called the GranTurismo Spyder.