A V12 open-top version of Mercedes’ flagship S-Class lineup, whose regional unveiling occurred last night, will be a rare sight on our roads – and an even rarer sight in the showroom.

THE most expensive road car Mercedes Benz has ever offered in New Zealand, an open top four-seater V12 grand tourer capable of 300kmh, seems too exclusive to put on the showroom floor.

Three editions of the S-Class Cabriolet – which joins pre-existing coupe and sedan editions of Benz’s flagship - are being made available to Kiwis.

The range comprises a factory-provided S500 and two cars that have been heavily fettled by the brand’s AMG division, all replicating what is already available in two-door hard-top form.

The entry model and the cheaper of the two AMGs, the S63, run biturbo V8 engines, but in different capacities, and respectively cost $292,600 and $379,600.

These models will be in general stock, with the S63 expected to become the volume seller, just as is the case with the coupe and sedan models with these powerplants.

Says spokesman Matt Bruce: "Typically a 63 is right in the sweet spot."

However, the new S65, which packs an engine that is restricted to just two other models in Benz-dom, a handbuilt 6.0-litre twin turbo V12 outputting a stonking 1000Nm – the most torque ever from a Benz road car of the modern era yet also a figure that, the maker assures, has been electronically pinned back - is determined too rich a picking to have on that level of consignment.

With the V12 having so far garnered just two sales this year in its other applications, this $461,200 car will only be available by indent, a local spokesman said.

That means buyers have to agree to buy before they try. Sign up includes laying down a significant deposit.

That’s a stipulation unlikely to put off the clientele, some of whom were probably in attendance at the car’s Australasian unveiling last night during Motorclassica, a swank annual event in Melbourne dedicated to automotive design.

The new Benz flagship was one of the few brand-new cars among an astounding collection of past era classics brought to the city’s historic Royal Exhibition Building, some for sale and all up for ‘best in show’ concours d’elegance consideration.

The selection of more than 100 veteran, vintage, classic and exotic vehicles ranged from the motorcycle that Steve McQueen rode in the film ‘The Great Escape’, a 1969 350 cubic inch V8 Holden Monaro and 1971 351 GT Shaker Ford Falcon from the same era that will likely keep local revhead adulation appeased to a 1930 Rolls Royce Phantom II that was originally owned by Bruce Ismay, the chairman of the White Star Line who survived the sinking of that outfit’s most famous ship, the Titanic.

The S65 doesn’t deserve comparison with the world’s most famous luxury liner, save in one sense: It makes an utterly grand statement. This car absolutely sets a high standard for prestige and huge power, though the 5.5-litre V8 S63 – which in packing 430kW and 900Nm has just 33kW and 100Nm less than the V12 – would have to be considered a pretty good understudy.

The S500 is also very swish, with a 335kW/700Nm 4.7-litre engine, is also no layabout.

It is not yet known how many Kiwis have laid down money on the AMG S 65, whose price could easily be ballooned with ticking of boxes for up to eight optional packages and other add-ons. The big ticket AMG-branded items are a high-performance ceramic composite braking system that adds $17,500 and a carbon fibre engine cover for $3425.

Until now, the V12 has only been available in an S65 AMG Coupe and the SL Roadster, which have co-held top price status with a shared sticker of $445,000. The S-Class sedan lines stops with the AMG V8 engine.

Most AMG products are about tyre-smoking kapow, but though the S65 Cabriolet has the goods to lay down a challenge to all but serious supercars in a straight line sprint, it is really too big - at 5044mm long and 1910mm wide - and heavy, at 2185kg, to challenge in corners.

The right-hand-drive edition also lose an agility assist afforded the left-hand-drive version, a 4Matic all-wheel-drive, because the steering system gets in the way.

No surprise, then, that is trumpeted by Mercedes as a luxury sports tourer than an outright racer and also as “perhaps the most beautiful S-Class of all time”.

But it is fast off the line, with Benz citing ability to propel to 100kmh from a standing start in 4.1 seconds – the same figure given for the S65 Coupe though, ironically, still 0.2s slower than the S63. The V12 runs to the same electronically limited top speed of 250kmh as the AMG V8 sister car although owners can bump that to 300kmh with the $2600 AMG Driver’s Package.

The S500, which is engineered with a nine-speed automatic whereas the AMG fare has a seven-speed that now comes with a special feature adding crackles and snarls on upshifts, is able to smack down a 0-100kmh time of 4.6 seconds.

Not having all-wheel-drive saves 60kg, but the Cabrio is 85kg heavier than the Coupe edition. Benz attests the gain would have been greater had it taken a metal folding hardtop rather than a soft fabric folding top.

The S65 is thirstiest of the three cabriolets, chomping through 12 litres of high-octane petrol per 100km, compared with 8.5L/100km for the S500 and 10.4L/100km for the S63 on the European combined test cycle.

Like the S-Class Coupe, cabrio variants are equipped with semi-active air dampers that can be adjusted for comfort or sports driving, although they miss out on the S-Class sedan and coupe's curve compensation feature to counter body roll.

Behind the rear seats, all the panels are different to those of the coupe, mainly to house the roof folding mechanism. Hidden roll bars wait to spring into action, fired by pyrotechnic charges should the worst happen.

Apart from the folding roof that goes up or down in 20 seconds while driving at up to 50kmh, equipment levels are basically the same as the S-Class Coupe, so very high.

Nappa leather seats, Burmester 13-speaker sound system with digital radio, so-called Airscarf neck warmer for the driver and front-seat passenger, heated rear seats and walnut high-gloss trim come with the cheapest version.

As is now becoming the norm for latest Benz product, it has a digital display that stretches from in front of the driver, where it shows a representation of traditional round speedo and tacho dials, to the middle of the dash for other functions such as phone connectivity, audio and sat-nav. The AMG versions have higher-side sports chairs than the S500, but these appear more suited to comfort than performance driving, and light up the night with LED headlights set with Swarovski crystals.

All variants get 20-inch alloy wheels, although the AMG versions get fatter, lower-profile tyres to complement their sports suspension.

The S65 was shown off at Motorclassica, now in its seventh year, because Mercedes is the ‘celebration marque’ of the 2016 event, the world’s oldest car-maker commemorating its 130th anniversary with a number of historic vehicles as well.

The model’s availability inspired the maker’s theme this year to be open-air driving, and while AMG’s velvet sledgehammer will attract plenty of attention, there is a handful of almost priceless vehicles on show.

Mercedes-Benz, the ‘Celebration Marque’ of the event, will show 20 vehicles in total — 12 of them convertibles plus a car whose potential for a roof was never given any consideration at the time, this being an 1886 three-wheeler, the first car from the brand.

Also on display were simply a stunning 540K Cabriolet from the late 1930s and a gorgeous 300 SL Roadster from the 1950s. The more modern ‘gullwing’ was also represented by an SLS AMG Black from 2013. That $528,150 version was the singlemost expensive Benz road car sold in NZ. But it was not a full production model and just one came here.

Mercedes-Benz Cars Australia/Pacific chief executive Horst von Sanden said the event was one of the most important on the automotive calendar in Australia, bringing car collectors and enthusiasts together in one place.

Arch-rival BMW, which has a habit of trying to upstage its homeland foe at the event, continued that practice by showcasing the BMW iVision future interaction concept, a vehicle that “hints at i8 Roadster” says the company.

It was first displayed in January, 2016, at the Consumer Electronic Show in Las Vegas and also provides a glimpse into the future of in-car technology, with advanced display screens and next-generation gesture control tech in evidence.