Mercedes-AMG has only scratched the surface of its V8 engine’s potential

Two things leapt out at me from the Mercedes-Benz pre-Paris motor show party and neither of them had anything to do with the mildly tweaked B-class on show there.

Instead both concerned the new 4-litre V8 engine powering both the Mercedes-AMG GT coupé and the C63 saloon and estate, both of which were being seen at a show event for the first time.

First is Mercedes’s assertion that its new twin-turbo V8 is actually more economical than a rival’s twin-turbo six-cylinder motor, and you don’t need to look any further down the road than to BMW in Munich to know which one is being talked about.

So the Mercedes engine has far more power – 503bhp in ‘S’ guise compared to 431bhp for the BMW M4 and M3 – yet it uses less or at the very least no more fuel.

In that instant everything I thought about downsizing to smaller engines with fewer cylinders went up in smoke. Both engines are new and twin turbocharged, but one has 4-litres and eight cylinders, the other 3-litres and six cylinders. 

To all the doomsayers who claim the days of large capacity, multi-cylinder engines are over, Mercedes for one appears not to have heard.

The second point was an aside from engineering boss Dr Thomas Weber who said this engine would mean even more V8 engines, not just for AMG but Mercedes-Benz too.

And why not? At the moment Mercedes makes four V8 engines, in 4.0, 4.7, 5.5 and 6.2-litre capacities. This clearly will not last. What Weber appears to be saying is that AMG will build 4-litre engines, presumably at a volume to enable it to replace the 4.7-litre engine, the only V8 not to be used in AMG cars. And does AMG have enough capacity to take this on and retain its treasured ‘one man, one engine’ hand-built philosophy? We shall see.

In the meantime, I can see the new engine becoming in time the only V8 in the line up. It’s an entirely modular unit that really is two 2-litre fours (such as you’ll find in an A45 AMG) sharing a common crank and its current maximum output of 503bhp is barely scratching the surface of its capabilities.

Given the A45 has 355bhp, a 4-litre V8 with 600 or even 700bhp is feasible, which is more power than any Mercedes road car in history. With that kind of potential up your sleeve, why would you use anything else?

One last thing – if a 2-litre four can so easily become a 4-litre V8, ’tis but a small step from there to a 6-litre V12 to replace the aged units used by the S65 and SL65 AMGs.