BMW M division claims its new twin-turbocharged 3.0-litre straight-six engine is every bit as good, if not better, than the glorious naturally aspirated 4.0-litre V8 powerplant it supplants in the new M3 saloon and M4 coupé.
The raw figures are certainly impressive. They say it kicks out an added 10bhp, at 424bhp, and more than 25 per cent extra torque, with what is described as significantly more than 369lb ft below 2000rpm.
No lack of grunt, then. But as I sit next to Martin Tomczyk, one of a trio of factory drivers BMW’s M division has brought to the unveiling of the new engine at a test track north of Munich, in an M4 coupé prototype mule ready to head out for a couple of hot laps, I’m not so sure the move to forced induction is going to be met with quite the same enthusiasm as that shown by the men from BMW M.
The sound the new engine makes lacks the sheer intensity of its predecessor, both mechanically and in the sound of the exhaust. As Tomczyk, a former DTM champion, fires the camouflaged coupé off the line with a heavy dumping of the clutch and a big dose of right foot, the primary aural accompaniment is an uncomfortable whooshing of the turbochargers – a pair of IHI units operating at a maximum 1.3 bar of boost pressure.
Up in to second, third and fourth gears, I detect a rising in the rate of revs, but whereas the mechanical attributes of the engine used to be a headlining act, they are now a distant play in the driving experience.
Down the slip lanes and through a series of witches' hats at speeds touching on 100mph, the revs rise then fall but the exhaust note remains disappointingly flat. BMW M division has developed a new cross flow muffler with flaps that open to direct the exhausts straight to the tail pipes at higher engine loads. It is supposed to enhance the sound.
When we return to the staging area, I let my feelings be known to a group of engineers. I’m told the engine lacks the latest developments, which comes as a bit of a relief. I can only hope the production car, on sale in the UK next May, sounds better.