With the debut of the 2018 Mercedes-Benz AMG GT and GT C Roadsters this coming fall, a key expansion of Mercedes-Benz’s sports car givings will be complete. These convertible models which is based on the GT Coupe are yet two more bolts in the automaker’s quiver intended to divert would-be buyers away from Porsche’s formidable 911 range.
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The Mercedes-Benz AMG GT was launched in 2015, along with the GT S Coupe, as a more fully formed two-seat sports car to replace the SLS. The GT S was quickly followed by the introduction of the GT R and GT C variants. It was just a matter of time until somebody in Germany got the bright idea to hack off the roof.
The Making of a Roadster
The process of changing the GT Coupe into a convertible, as is typical, entailed considerable efforts to recoup the stiffness lost when lopping off the roof. Engineers beefed up the sills, the cowl and the bulkhead aft of the cabin. Use of lightweight materials like carbon-fiber sheet molding compound for the Roadster’s decklid and magnesium in the motorized soft top’s frame kept the weight gain to a minimum. Nonetheless, Roadsters weigh 3,683 pounds (GT) and 3,825 pounds (GT C), some 121 and 77 pounds more, respectively, than Coupes. The soft top is motorized, of course, and can deploy or stow at speeds up to 31 mph in roughly 11 seconds.
Not that the stopwatch notices. Base Roadsters are made to hit 60 mph in 3.9 seconds, and GT C Roadsters need just 3.7 seconds — results that are identical to those of the respective Coupes. All GT Roadsters are propelled by the same 4.0-liter twin-turbo V8 found in the nose of their Coupe counterparts. Generating 469 horsepower and 465 pound-feet of torque, the base GT engine handily outdoes the Porsche 911 Carrera S (420 hp, 368 lb-ft). Meanwhile, GT C Roadsters and Coupes also get an additional slug of thrust — lower compression pistons, larger turbos, a higher-capacity fuel pump and increased boost pressure (plus a revised engine calibration) conspire to produce 550 hp and 502 lb-ft of torque.
Power is emptied to the rear wheels through a rear-mounted, seven-speed dual-clutch automatic transaxle. Gearbox ratios (first, seventh and final drive) are also tweaked for the GT C, resulting in shorter overall gearing in all gears except first.
An Interior for Two
The Roadster’s cabin still has the snug, cockpitlike ambience of the Coupe’s. A wide console with eight controls takes up the lion’s share of the available width. It’s an intimate place, more so than a 911’s cabin, though less cramped than the old SLS Roadster.
The optional AMG Performance seats look great, but we couldn’t find a comfortable seating position even after a couple of hours in the saddle. At least those seats’ Airscarf feature can breathe warm air on their occupants’ necks, if needed.
GT Spotter’s Guide
Base GT Roadsters wear 19-inch wheels, a mechanical limited-slip diff and fixed dampers as standard equipment. GT C models can be recognized externally by their wider rear fenders and rear bumper. The former bulk up the width of the car by more than 2 inches, while the latter has three prominent perforations.
GT C models also have a raft of enhancements under the skin such as an electronically controlled differential, rear-wheel steering, continuously variable dampers, electronically variable engine and gearbox mounts, larger-diameter front brake discs, wider rear wheels and wider tires all around. They also get a Race setting on the AMG Dynamic Select controller that keys up a more aggressive transmission shift schedule. Some of the GT C’s features can be optioned onto a base GT.
On a Phoenix-area test drive of both variants of the GT Roadster. Regardless of which model was piloted, the drop-top feels supremely rigid. If there’s any loss in rigidity due to the loss of the roof, it’s not detectable from behind the wheel.
In fact, the Roadster’s driving demeanor doesn’t stray an iota from that of the Coupe’s. The vehicle always feels coiled to strike, hungry to attack the next apex and catapult you to the next one. Its power delivery is seamless and immediate — if you want to find turbo lag, you’re going to have to hunt for it. It is completely a nonissue. And while the gearbox is a fine performer no matter the pace, it still comes up short of the preternatural reflexes of the Porsche PDK dual-clutch box. Then again, so does everyone else’s transmissions.
Irrespective of all the fireworks directed to the GT C Roadster’s rear wheels, there’s a shocking amount of traction on tap when accelerating hard out of corners. It just digs in and positively hurls itself forward. The GT C’s sharp disposition has a downside when on country roads and freeways because road noise from its short-sidewall tires is a constant companion.
Which One Would be Ideal?
In many areas, the base GT Roadster makes for a more convincing execution of an open-air vehicle — its steering is a bit more natural and the ride quality more supple, not to mention there’s less road noise. Yes, the base GT is slower than the GT C, but it’s still stinkin’ quick. As a package, the base GT is more in line with what we’d expect would resonate with drop-top buyers. Now if only there were a way to pair the base car’s more honest chassis and svelter hips with the GT C’s engine.