Around 90 per cent of the GT’s body is made from aluminium, the front section ahead of the front axle being made from magnesium to reduce inertia when the car wants to change direction and theoretically improving agility.
The boot lid is made from steel and strangely, the reason is to save weight, explains Mercedes-AMG chairman, Tobias Moers. “We used steel for the boot lid because it provided a lighter solution than using aluminium. The thickness of aluminium needed to achieve the profile I wanted was simply too great.” The bodyshell weighs just 231kg of the total 1540kg kerb weight.
AMG has dropped weight with the powertrain too. The new twin-turbocharged 4.0-litre M178 V8 engine is a study in downsizing, dropping more than two litres from the previous naturally aspirated 6.3-litre V8 and burning 32 per cent less fuel.
It’s offered in 456bhp and 503bhp form here with dry-sump engine lubrication allowing serious track use if desired. The higher of those numbers gives a power to weight ratio of 326bhp per tonne.
The engine is based on the new four-cylinder direct injection petrol engine launched last year in the A-class and shares the same bore and stroke.
AMG designed that engine, too, and Moers says the key to efficiency and power lies in the design of the spray-guided direct fuel injection and combustion chamber, which is also carried over from the four-cylinder engine.
The lack of a ‘wet sump’ hanging beneath the V8 allows it to be mounted lower in the car, moving the overall centre of gravity closer to the ground for better handling and road holding.
The 7-speed DCT transmission (also used in the SLS) is mounted on the rear axle and combined with the front mid-engine configuration, this adds up to weight distribution of 43 per cent front, 57 per cent rear.
Purists may mourn the passing of the brutish naturally aspirated V8s that have gone before and feel that downsizing and turbocharging to increase efficiency are sacrilegious. But consider this; turbocharging creates an opportunity for easy power increases in the future by turning up the boost.
The V8 has a forged steel crankshaft and connecting rods. In theory it should be capable of even higher power outputs, but is it in reality? “Put it this way,” says Moers, “at 503bhp this engine is not highly stressed.”
What about the thorny question of turbo lag then? “Forget it,” says Moers, emphatically. Using computer simulation, AMG found it could achieve a more favourable design of intake system to optimise the performance of the turbo compressors and eliminate lag. “The response is like that of a naturally aspirated engine,” Moers insists.
It’s an aggressive package. Taking all those things into account, the low centre of gravity, high power and carefully thought out weight distribution with the emphasis on agility, you can almost imagine what it feels like to drive without the car turning a wheel. Moers helps us out. “It’s very agile with a lot of traction at the rear axle and is not at all tricky to drive.
“My personal philosophy is that every car has to be balanced and stable with the ESP switched off.”
Mercedes research and development boss Professor Dr Thomas Weber said the new car “takes us into a segment already occupied by respectable competitors.”
With the potential for more derivatives and all-new new sports models, Mercedes-AMG is bringing uncompromising technology to the table and clearly means business. “Mercedes-AMG sales are currently 30,000 a year globally and next year it will be 40,000 at least,” says Weber. “But that’s not the end of the story and there’s huge growth potential.”
Read more about the Mercedes-AMG GT
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