MERC-AMG GT4’S secrets
Weight and cost issues mean 600bhp four-door model will sit on modified C-class and E-class platform
E-class floorpan is key
The need to offer fourwheel drive is behind Mercedes-amg’s decision to base its upcoming four-door GT4 model on the floorpan of the latest C-class and E-class, rather than its own aluminium structure.
The production model, to be revealed at the Geneva motor show in March, is visually based on the concept GT4 shown at the same event last year. After the SLS AMG and current GT, according to Marc Buttstädt, AMG’S product manager, it is the third AMG to be “100% developed by AMG” and he promised “it will be a lot of fun”.
Although the aluminium monocoque of the existing two-door GT might outwardly seem suitable for development into a four-door model (in the way that the Aston Martin’s VH architecture spawned the fivedoor Rapide hatchback), it isn’t suited to making a big saloon.
The problem is that it has a transaxle gearbox. That’s essential for giving the GT the slight (53%) rearward weight bias it needs to work as a powerful, rear-drive sports car, according to AMG’S chassis team leader, Markus Hofbauer. But it rules out being able to offer the car with four-wheel drive, which is “essential for winter driving” and to give the stability expected by saloon car drivers, because taking drive back to the front is complicated and heavy.
One alternative, Hofbauer says, would be to give fourwheel-drive versions of the GT4 a hybrid powertrain, with electric power to the front axle – which would also give the potential for it to be a part-ev.
Ultimately, though, cost and weight considerations mean that the GT4 – the name of which is likely to change for production – is being developed instead on a modified version of the MRA platform, which sits beneath the C-class and E-class.
AMG boss Tobias Moers has previously told Autocar that MRA “gives us a floorpan; it doesn’t limit us”, so it can still choose whatever dimensions it pleases for the GT4. It’s just that its gearbox will be connected to the engine at the front, where a four-wheeldrive takeoff is much easier.
The car will launch as a 4.0-litre, twin-turbocharged V8 model with 600bhp, with an 800bhp or so hybrid model coming later.
Hofbauer told us that he’d prefer a drivetrain with a hybrid system that was connected to the crankshaft and existed to increase performance and fill in any torque gaps created by turbo lag, rather than a hybrid that provided a separate electric drive. Tellingly, that’s the type of powertrain that was previewed in the GT4 concept too.