First drive: Benz GT Roadster to kick off at $284K

UPDATED: 31/03/2017THE latest open-top car to wear the three-pointed star, the Mercedes-AMG GT Roadster, is set to carry a premium of $25,000 over the GT Coupe when it arrives in Australian showrooms about September to take on the likes of Porsche's 911 Cabriolet and Maserati GranCabrio.

The two-seat, two-door sportscar – Mercedes’ sixth open-top model – will come in two specifications, GT and GT C, with the former priced at $284,000 plus on-road costs - $25,000 more than the matching GT Coupe - and the latter $54,000 dearer, at $339,000.

That pricing places it smack in the middle of rival Porsche’s extensive eight-variant 911 Cabriolet range, but crucially make the GT and GT C up to $100,000 cheaper than Porsche and Maserati equivalents.

The GT C Roadster becomes the most expensive of the six GT Coupe and Roadster variants in the revised range to be rolled out in the third quarter of this year.

Mercedes’ GT Roadster joins the C-Class Cabrio, E-Class Cabrio, S-Class Cabrio, SLC Roadster and SL Roadster in the Benz convertible range, giving the company the most extensive luxury open-air selection on the market.

The GT Roadster is the only one of these vehicles designed and built from the ground-up by Mercedes-AMG, with all the performance and sophistication that entails.

Pricing and final specifications for the new-look GT line-up will be confirmed closer to launch, but Mercedes-Benz Australia/Pacific has acknowledged that both the Coupe and Roadster will include a new variant, the GT C, for the first time.

In the Coupe line-up, this slots between the mid-range GT S and race-bred GT R.

Timed to arrive in Australia just in time to take advantage of the fine spring weather in the third quarter of this year, the GT and GT C Roadsters have a soft-top that opens in just 11 seconds at up to 50km/h.

Sitting on a frame of lightweight materials that includes magnesium, the three-layer roof – available in three colours – folds away behind the seats in a Z shape to save space and maximise cargo room.

Of course, the first thing we did upon climbing into our bright yellow GT C test car at the global media launch in Phoenix, Arizona, was to make the roof disappear, revealing a drop-dead gorgeous drop-top design that – with all due respect to the coupe version – was meant to have the roof removed all along.

The second thing we did was to touch the ‘start’ button, knowing full well that the booming AMG 4.0-litre V8 would rend the crisp morning air. Yep, it is still one of the most satisfying engine notes, at idle or full bellow.

These Roadster siblings share the same upgraded powertrains as their revised coupe counterparts, with the base model GT’s biturbo V8 sending 350kW of power and 650Nm of torque to the rear wheels through a seven-speed dual-clutch transmission.

The GT C, which becomes the flagship roadster in the absence of an ‘R’ version like the coupe, comes with 410kW of power and 680Nm of torque, sufficient to propel the GT C from zero to 100km/h in 3.7 seconds, which is about 0.3s faster than the GT Roadster.

Top speed for both variants is above 300km/h, with the C allegedly capable of hitting 316km/h.

On America’s strictly patrolled roads, we did not see any of the above, but the sheer force of acceleration out of corners on mountain roads was an uplifting experience we will not forget in a hurry.

Considering the GT has the same-sized V8 and transmission as the GT C, the latter is curiously more thirsty, chewing 11.4 litres of premium unleaded on the European combined test cycle compared with 9.6L/100km for the GT.

Stick the boot into it and those figures become a faint wish as the big turbos and fuel injectors get to work.

Despite a shortfall of 20kW over the 430kW GT R, the ‘C’ borrows heavily from the ‘R’, taking the muscular, wider rear body design (+57mm) to accommodate fatter 20-inch back wheels, along with mechanical items such as active rear-wheel steering, electronically controlled limited-slip differential, 390mm compound front brake discs and variable performance exhaust to let the big V8 speak lustily.

These are big pluses for the GT C – assets that may make the more expensive version the top seller in Australia.

The fat behind is a good look, but it is the mechanical enhancements that provide the real benefit in our eyes. The rear-wheel steering helps the roadster point through corners with unflustered calm while also helping low-speed manoeuvrability – handy in such a wide car.

Combined with AMG’s ride-control sports suspension on the GT C, this system starts to make the extra expenditure for the up-market Roadster look reasonable.

No fewer than five electronically controlled driving modes are available via a knob on the console on the GT C (four on GT), ranging from Comfort to Race, but we found ourselves switching between Comfort and Sports for most of the journey, depending on the road.

The Sports+ mode tended to be a bit manic, while we weren’t tempted to try Race on the open road where safety systems such as electronic stability control are left in place by the wise.

Unusually, the GT C has 19-inch wheels at the front and 20-inch rims at the back, while the base GT has 19-inch wheels all round. However, the test GT we drove had 19s on the back, indicating that they will be offered in an option pack (and that Mercedes is not beyond gilding the lily a little on media launches).

Both Roadster variants get the R’s automatically closing louvres behind the grille to improve aerodynamics, at least in cool-weather driving. That grille, by the way, is the stylish new signature AMG vertical bar design, dubbed Panamericana after the racing cars, that will appear on all AMG variants.

To make up for the loss of rigidity afforded by the roof in the Coupe, the Roadster’s aluminium space-frame platform has been reinforced with stronger side skirts and additional braces.

So-called scuttle shake is all but absent in the GT Roadster, proving again that the Germans really do understand body engineering in all its forms.

The only irritant to our ear was a rattle under the dash in two of the three cars we drove, but as these cars had been put through a two-week mill by journalists from all around the world by the time we got to them, that is not too shabby.

A unique feature of the new GT Roadster is a lightweight bootlid made from a new process combining carbon-fibre with a sheet moulding process.

Lifting that lid reveals a tight boot space that would hold about two large sports bags. Of course, the folding roof swallows the rest.

And don’t go looking for lots of cubbies in the cabin – space is at a premium there, too.

Both GT Roadsters get AMG sports seats, but the GT C gets the extra bling, with a mix of suede-like microfibre and leather upholstery in place of the fake leather on the standard variant. The microfibre also extends to the chunky sports steering wheel on the GT C, in place of a Nappa leather grip on the GT.

In any drop-top car, roll-over safety is paramount, and in this case, permanent roll hoops behind the two seats are there, just in case.

Being a Benz, every possible safety device is loaded into the car’s armoury, from adaptive cruise control with autonomous braking to lane keeping control.

Our test drive took all day, but we are not complaining. What a day it was.

2017 Mercedes-AMG GT Roadster pricing*

GT (a)	$284,000
GT C (a)	$339,000

*Excludes on-road costs