NEW YORK MOTOR SHOW: Mercedes-AMG C 63 Cabriolet

The smallest convertible in the Mercedes-Benz line-up has been stuffed full of AMG’s biturbo V8, creating a tarmac-burning monster out of a humble blow dryer.

Affalterbach’s hand-built 4.0-litre V8 will push up to 375kW of power through to the rear wheels of the four-seat C-Class convertible when it hits European streets this summer.

The strongest of the two C 63 Cabriolets, the C 63 S, will hurl itself to 100km/h in 4.1 seconds, which is enough to frighten most people with preconceived notions of what the convertible version of a Mercedes-Benz coupe should be like.

The entry-level C 63 Cabriolet will have a paltry 350kW of power, though the 25kW shortfall only costs it a tenth of a second in the sprint to 100km/h.

Both cars are limited to 250km/h (with 280km/h options), though they achieve both this and their straight-line sprinting despite a large, seven-seat SUV-like kerb weight of 1910kg, or 1925kg for the C 63 S.

To be fair on AMG, though, that’s a wet weight, including a 68kg allocation for the driver (have they seen the people who drive AMGs?), 7kg for the luggage and a fuel tank that’s 90 per cent full. Nevertheless, it’s too hefty for its overall size to be admired for its engineering.

Benz claims the C 63 Cabriolet is the only convertible in the class that offers a V8 engine, which discounts the Audi RS 5 and ignores the performance potential of the BMW M4 Convertible’s twin-turbo in-line six-cylinder powerplant. But as good an engine as it is, the 3.0-litre BMW doesn’t make the same sort of R-rated noises as the 4.0-litre AMG motor.

It’s already fitted to the C 63 sedan, wagon and coupe, and is a wet-sumped relation of the hot-vee motor, with its turbos sitting inside the engine’s 'vee', that made its debut in the GT and GT S AMG coupes.

The 3982cc powerhouse reaches its peak power from 5500rpm to 6250rpm in both cars, though the S version delivers 700Nm of torque from 1750 to 4000rpm, while the standard unit is 50Nm shy of its sibling.

"The C-Class is a decisive factor in our company's success,” AMG President Tobias Moers insisted.

“The new combination of intensive open-air ambience and powerful V8 engine is unique in the segment and perfectly supplements our large C-Class range.”

To make up for any perceived softness in the body style (four-seat convertibles are not known for their Nürburging lap times), the C 63 AMG Cabriolet gets the full AMG kit bag of go-fast tricks.

It controls the four-link independent rear suspension via adaptive damping, which lets the driver choose from Comfort, Sport and Sport + settings to set up the car for each situation and mood.

The stock C 63 Cabriolet rolls on 10-spoke 18-inch alloy rims draped in 255/40 R18 front tyres and 285/35 R18 rears, while the more powerful of the two cars bumps the rubber size up to 255/35 R19 front tyres and 285/30 R19 rears. Other rim styles are options, including a 20-inch rim.

It hooks the boots up to the car through the same rear axle AMG developed for the Coupe, so it has a new rear axle carrier and its wheel bearings sit 25mm further out than in the sedan or the wagon, plus it has new wheel carriers, more negative camber and its elastokinematic tuning is a lot stiffer.

The fight for traction and ride control continues into the differential, where, confusingly, the two C 63 Cabriolet siblings use completely different systems to accept all that power from the back of the seven-speed automatic transmission, then shoot it out to the rear wheels.

The C 63 AMG Cabriolet uses a mechanical limited-slip differential, but the C 63 S Cabriolet has an electronically managed version, which AMG claims works faster, more precisely and lifts the car’s performance potential even higher.

A familiar player has the governing role in pushing the drive to the back, though, with AMG’s familiar MCT-7 seven-speed transmission doing the shifting. Effectively, it’s a beefed-up version of Benz’s older seven-speed automatic transmission, but with a manual-style clutch pack replacing the torque converter for better shifting.

Then, because C 63 AMG Cabriolet buyers aren’t much into manual transmissions, it controls the shifting electronically like an automatic transmission would. It’s effectively a hybridised unit that can also be shifted by gearshift paddles or left to its own devices.

It has a bunch of other tricks, too, including a new sailing function attached to its comfort mode, which, when the driver comes off the accelerator pedal, unhooks the clutch from the power train at speeds between 60 and 160km/h to lower fuel consumption.

It also delivers Sport, Sport Plus and Race modes above that, and that also changes the skid-control and traction-control parameters. It hauls itself down from speed using 360mm disc brakes at all four corners, thought the S pushes that up to 390mm and has the option of a 402mm carbon-ceramic set of anchors.

There is a sharper electro-mechanical power steering system, with a 14.1:1 ratio, and it also uses dynamic engine mounts that can run soft to absorb noise, vibration and harshness but can stiffen quickly to prevent the engine’s lateral momentum hampering the cornering performance.

It also uses the same exhaust system as the C 63 Coupe, with exhaust flaps that are linked to the transmission settings and can be opened or closed to deliver a more intense sound as the gases divert down either a short (more noise) or long (less noise) route to the exhaust tips. There’s also the option of a Performance exhaust, which has its own controlling button.

Visually, the design team carried the C 63 AMG Cabriolet’s main grille and tail elements across from the Coupe, including its deep front splitter and quad exhaust tips.

The front wheel-arches flare out 64mm at the front and 66mm at the rear to give the car a fatter stance to match its tyres, while the longer aluminium bonnet is 60mm longer.

The car carries a 355-litre luggage capacity when the multi-layer cloth roof is up, or 260 litres when it is tucked away inside the boot.

The new C-Class Coupe range – including the C 63 AMG – arrives in Australia in May, followed in the fourth quarter of this year by the all-new C-Class Cabriolet range, with the C 63 Cabriolet to follow soon after.