The combustion-engined version of the next-generation BMW M3 has surfaced in tests at the Nürburgring – and the super-saloon could continue to offer a manual gearbox.
Speaking to Autocar at last week’s Goodwood Festival of Speed, BMW M boss Frank van Meel said the division's petrol performance cars will offer manuals for “as long as possible”.
He highlighted that sales of the smaller M2 coupé in the US – a market traditionally dominated by automatic gearboxes – are actually split 50:50 between autos and manuals.
He also pointed to the engagement fostered by rowing your own gears: “We want to have this mechanical connection, shifting by yourself. It's an emotional thing, it's not just an engineering thing, and it's still there.”
But offering a stick shift in a mainstream car is becoming harder, van Meel added: “The supplier base is getting smaller, and with all the driver assist systems it's getting more difficult to disconnect the drivetrain. Then you're disconnected from your driving assistance system as well as all the mild hybridisation systems.”
Yet this “doesn’t mean it isn’t possible”, he said, adding: “We intend to keep the manual as long as possible.”
M3 keeps its signature straight six
In either case, key to the appeal of the next combustion-engined M3 will be the retention of its turbocharged 3.0-litre petrol straight six.
This diverges from the path followed by BMW's German rivals: the Audi RS5 kept the RS4's 2.9-litre V6 but added plug-in-hybrid hardware, while the Mercedes-AMG C63 moved from a V8 to a four-cylinder PHEV system.
BMW's ‘S58’ engine, also used in the M2 and M4 coupés, was recently updated to meet the Euro 7 emissions standard in a significant engineering effort.
It was redeveloped for pre-chamber combustion, in which a small amount of fuel is detonated in a small space just before the fuel reaches the main cylinder. This creates a highly energised 'jet' that then lights the fuel in the main chamber.
This, BMW claims, is much quicker than a traditional spark plug, which brings several benefits. Chief among them is increased greater energy efficiency, and therefore greater fuel efficiency, which reduces emissions.
Van Meel told Autocar last year: “The whole story is about driving with lambda one [when the air-fuel ratio for combustion is perfectly matched], so you have to keep that. And there's no cooling; normally, if you are in high-performance situations, you cool using the fuel. With Euro 7 that’s impossible, so you need to find different ways of avoiding temperature build-up.”
The new combustion process also helps to alleviate premature fuel detonations (knock), which allows it to be run at a higher compression ratio, thereby boosting power.
The updated engine also gets new variable-geometry turbochargers.
These measures meant BMW could mitigate any loss of power from adjustments made to meet the requirements of Euro 7 – and the firm claims they also create a throatier induction and exhaust sound at high revs.
