Minimising mass is all very well, but what
about the turbo lag you ask? That was, after all, one of the biggest challenges
that the engineers faced. Well, if ever there was genius in the oily bits it’s
here. You see, in a regular turbo, the turbine that forces pressurised air into
the intake spins with the forces of the exhaust gasses. So, until the engine
gets up to speed, the exhaust gasses don’t spin the turbine fast enough for the
turbo to engage – and therein lies the cause for turbo lag. In this case, the
M3 gets two small turbos – each working on two halves of this in-line six. The
crucial part is that the turbine is kept spinning between 80,000-90,000rpm (out
of a maximum turbine speed of 190,000rpm) at all times regardless of engine
speed.
Switchable
modes turn the BMW M3 from comfortable cruiser to track weapon
What this means is that the turbo is
practically always up to speed – there’s simply no lag to speak of at all. And
the way they’ve achieved this is to variably interrupt ignition and injection
in up to five of the six cylinders depending on the driving conditions and
inputs of the driver. I, for one, couldn’t tell that this was a turbocharged
engine. It felt every bit as free revving, shrill, urgent and on-the-boil as
the straight-six from the E46 M3 of two generations ago.
There
are plenty of premium materials at work in the M4's cabin, making you feel like
you're in something special
What of the sound then? Well, I can’t say
that they’ve been quite as successful in that respect. At idle, the engine
sounds a little agricultural – as all direct injection engines do. It,
nevertheless, sounds angry, as if it’s concealing a lot of horses – which, of
course, it is. When you step on the gas with some urgency, as you tend to do in
a car of this nature, the exhaust sounds pretty throaty and angry. It doesn’t
quite sing like a traditional straight-six, but it still sounds pretty good all
the same. The problem occurs at medium engine speeds, at which point the engine
note sounds synthesized and unnecessary. Perhaps this is because you know that
the exhaust note is, in fact, synthesized – i.e. like the M5, it’s fed into the
cabin via the speaker system. Whereas, in the M5, you could say that it’s
actually required since the turbocharged V8 is quite muted, I’m not sure it
serves any purpose in the M3. Quite the opposite actually – at speed on the
highway, the noise from the massive tyres (255/35 ZR19’s in front and 275/35
ZR19’s in the back), plus the noticeable engine note, can get a little
intrusive.
BMW
M3's front track is stretched to 1579mm, 34mm up on the old version
But we didn’t come all the way to Portugal
to just coast on the highway. So, we headed to the Portimao track – a couple of
miles from the Algarve coast. And if I were still a little concerned en route
to the track, I needn’t have worried. Turn a wheel in anger on a track, and the
M3 just comes alive. And how! If the electric steering felt a little numb on
the street, on the track it simply feels pinpoint sharp, beautifully weighted,
and incredibly responsive. It’s as instinctive as the best hydraulic steering
racks. The variable electromechanical rack-and-pinion setup, after all, was
completely redesigned for the M3. In fact, the M-division recruited the
foremost steering engineer from BMW to single-handedly develop and test the
steering on the M3 and M4 to ensure that it’s absolutely spot-on and as close
to a hydraulic unit as possible. All I can say is that it’s a job well done –
he deserves another promotion!
