In theory at least, we’re at best grudgingly accepting the current trend of swapping large capacity normally aspirated engines for smaller units using turbos to make up the difference.
True fuel consumption and emissions can be improved this way, but at what cost? The first victims are usually the throttle response and noise.
But not this time. AMG is in the process of replacing its much loved 6.2-litre V8 with a 5.5-litre direct injection ‘biturbo’ motor. It’s first been fitted to the facelifted CL-coupé, which not only uses a staggering 38 percent less fuel, but has an extra 16 horses to prod the total up to 536bhp and a whacking 125lb ft more torque.
Impressive but not that difficult to predict. What these numbers don’t prepare you for is the ground-trembling thunder, and that’s just when you start the thing up.
Large turbo engines aren’t meant to sound like this. Nor are they meant to respond to the throttle like the CL 63, either. The secret would seem to be not more turbo pressure, but less. Because the engine is still large, Mercedes can afford to blow only moderate amounts of boost through it, which means the engine can run a compression ratio of 10.0:1, a number you’d normally associate with a normally aspirated car.
So there’s no off-boost lethargy at all, or any sudden uncontrollable bang in the back when it kicks in. Any revs in any gear and the thing just flies.
