It looks like Mercedes-Benz will be phasing out normal aspiration from its AMG cars, with the exception of the SLS AMG for now. The M156 is the V8 engine in the confusing “63 AMG” range of cars. Now I say confusing because the engine isn’t really a 6.3 litre, but a 6.2 litre since it displaces 6,208cc. It makes over 500 horsepower in various stages of tune, with the highest being 563 horses in the SLS AMG where it has been massaged and known as the M159 instead.

Replacing the M156 will be a new M157 – a 5.5 litre (5,461cc) V8 engine with twin turbochargers and direct injection, producing between 544hp up to 571hp. In 544hp tune, the engine makes a massive 800Nm between 2,000rpm to 4,500rpm (1.0 bar boost), while the 571hp version produces 900Nm (1.3 bar boost) between 2,500rpm and 3,750rpm. The engine is a bore-biased engine, with its pistons measuring 98.0mm x 90.5mm.

This engine will be showcased in Geneva installed in an S-Class mated to an AMG SPEEDSHIFT MCT 7-speed automatic transmission. That S-Class will be called the S 63 AMG. It will go from 0 to 100km/h in 4.5 seconds with the 544hp tune, while with 571hp tune (which AMG calls the AMG Performance Package), 0.1 seconds is shaved off that number. The AMG Performance Package will also increase the top speed limiter from 250km/h to 300km/h. I thought AMG was the performance thing for Mercedes-Benz cars but now it seems that the performance version has a performance version!

For the first time, an AMG engine will feature direct injection with spray-guided combustion and piezo-electric injectors. Other notable specifications also include a full aluminium crankcase with cast-in Silitec cylinder liners, a Bosch MED 17.7.3 ECU, four-valve technology with electromagnetically adjustable camshafts, an air/water intercooler in between the V-bank, generator management and a start/stop function as standard.

So now the ’63 AMG’ cars are turbocharged. The other AMG engine in the ’65 AMG’ cars is already twin-turbocharged. That monster is a 3 valve per cylinder twin spark 6 litre V12, making 604 hp at 4800-5100 rpm and a massive 1,000 N·m of torque at 2000-4000 rpm! 12 cylinders and twin spark means that engine has 24 spark plugs – a huge bill when a spark plug change is due, but probably no sweat to an owner of such a car.