Back in 2011, one of the most interesting rumors floating around was the one around BMW allegedly building a V6 engine for the F80/F82 M3/M4. At the time, our own Hugo Becker said:
“The question for BMW is what do they stand to gain by introducing a V6 in the next M3. For one thing there is less of a nose heavy weight penalty for a V6 than an in-line six. You give up the smoothness of the in-line 6 in either 60 or 90 degree V implementations. And you create additional work for audio engineers with a 90 degree V.
A 60 degree V6 can be derived from the existing V12. Because of the narrow V angle it would probably use a turbo on each bank with conventional exhaust. It would be smoother sounding than the 90 degree V6, but would have two hot zones in the engine compartment.
A 90 degree V6 makes some sense if you want to use a twin scroll turbo. It would be placed in the V and take exhaust from either bank of cylinders much like the current M V8s. It’s drawbacks are the need for a crankshaft with offset journals (to even the firing impulses) and of
course the less than pleasing sound emitted.
Frankly – BMW has taken pains over the years to emphasize the long hood that speaks of an in-line six and rear wheel drive. I believe there are only two mainstream auto manufacturers of in-line six engines left, BMW and Volvo (I don’t want to count the massive in-line six marine diesels still being built). I do not know why BMW would want to introduce a V6 – it would be a bespoke engine for the M3 initially, if the rumors are accurate. If it’s a 90 degree V6 it will require more development time to get it ‘just right’. And the primary purpose of a V6, extending the power options for FWD cars into C and D class ranges, is outside the scope of where BMW wants to take FWD cars from what I understand.”
Often asked, BMW engineers have elegantly dodged our question whether V6 powerplants have a chance to become reality for the Munich brand. The question was usually met with a smile and a shoulders shrug. But today, Jason Camisa of Road & Track, a journalist close to the brand, says that the Munich engineers indeed build and test prototype V6 engines, an internal policy that BMW has enforced. Camisa also mentions that the results from the V6 engine testing don’t met the rigorous engineering standards imposed by BMW.
At the moment, BMW remains the sole champion of the straight-six. Munich engineers admit that they regularly develop and test prototype V-6s, per internal policy, but say the results don’t come close to meeting company noise and harshness standards. Mercedes-Benz must not have such stringent benchmarks. Once renowned for its silken inline-sixes, Stuttgart phased out those engines and began building V-6s out of its V-8s during the dark, cost-cutting days of the marque’s DaimlerChrysler ownership. As the sting of that failed merger continues to fade, so will the company’s coarse, complex, 90-degree V-6, which is being retired in favor of a 60-degree unit. This stopgap engine, which fits into the vee-focused packaging of Mercedes’s current lineup, is noticeably smoother than the 90-degree unit, but its exhaust still sounds like Fran Drescher on Spanish fly—not the voice you want your luxury car to sing with.
For now, BMW is focusing exclusively on building some of the best straight inline six engines and the latest powerplants have proven to be quite remarkable. Will BMW launch a V6-powered car in the future? Time will tell, just look at the history of Formula 1.
Full article on V6 engines can be found here.