New Mercedes-AMG GT tech secrets revealed

Mercedes' new GT goes on sale this month, featuring a lightweight aluminium chassis and a new 4.0-litre V8 engine. We get the inside story on how the GT was made
9 October 2014

An all-new car with a new architecture and engine, the Mercedes-AMG GT is designed to push deep into territory occupied by the likes of Porsche, Jaguar and Aston Martin. 

Available in standard form or S versions wearing price tags of around £95,000 and £110,000 respectively, the GT will go on sale in Europe from the first quarter of next year with right hand drive versions reaching the UK in September - though order books open later this month.

Considering AMG started life as an independent tuning firm back in 1967 its complete integration with the Mercedes brand today is extraordinary. Even more so is the fact that Mercedes-AMG has become a sub-brand covering the entire spectrum of Mercedes models.

The new GT though, is something else. Not a heavily breathed-on existing model, it’s the second car from the bespoke tuning wing of Mercedes after the SLS to be produced from scratch. 

The GT has an advanced aluminium-based chassis using similar construction techniques to mainstream cars like the C-class. This is significant because the use of exotic F1-style carbon fibre tubs is costly and restricts volumes. Using aluminium for the core of the new GT opens up the way for an entirely new family of sports cars, including roadsters, built in much higher volumes. 

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. 

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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.”

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Jaybond

9 October 2014
That explains why the hp figure in this car is not really that high to make it more accessible for the masses in terms of price and performance. The trend to make the entry level supercar to be more & more powerful seems getting ridicilous. Hopefully Ferrari will enter this segment as well.

giulivo

9 October 2014
Since this is essentially two A45AMG engines joined up at the crank, and those have originally 355PS each, this one could produce 710PS, so I am not surprised that it is "not stressed", detuned by almost 30%.

Not my car, I would need 5 more seats, but really beautiful nevertheless. The rear end is very 928, which is a good thing.

Motormouths

9 October 2014
giulivo wrote:

Since this is essentially two A45AMG engines joined up at the crank, and those have originally 355PS each, this one could produce 710PS, so I am not surprised that it is "not stressed", detuned by almost 30%.

Hate to be pedantic, but the A45AMG has 360PS, which equates to 355bhp. And like you say, the scope for extra power from this V8 makes you wonder exactly what a Black Series version the GT could be capable of. I'm eagerly anticipating Aston Martin's next generation of cars for the same reason.

japes

10 October 2014
...at last a Merc with some simplicity of line and some elegance. Still trying too hard tho...c'mon Merc you need to have more confidence in what you stand for. Cut the over styled bling.

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