Open M3
 It was never a secret that the new M3
would soon be joined by an open top
version and April will see the M3
Convertible on sale in the UK. Based on
the retractable hardtop configuration
as used in the current 3-Series convertible
range, the open-air M3 shares its mechanical
specification with the Coupe and newly announced
Saloon.
The folding steel roof does carry a weight
penalty of course, so the 0-60 sprint is half
a second down... but 5.3 seconds isn’t what
you’d call sluggish.
What is a surprise though is the fact that
the convertible brings with it an entirely new
transmission option for the M cars and for
BMW in general: out goes the familiar SMG
gearbox and in comes the new seven-speed
M Double Clutch Transmission, or M DCT in
BMW-speak.
That might sound like the marketing
department just fancied some new initials
to play with, but the reality is a fundamental
change in engineering principles with the
new system working along similar lines to
the acclaimed VW/Audi DSG set-up.
 Essentially the SMG gearbox is a standard
manual gearbox with computer-controlled
actuators bolted to the case which push the clutch arm in and out and select the gears
for you – clever stuff for sure, but underneath
it all, very familiar technology. The Double
Clutch Transmission however, is almost two
gearboxes in one and uses two clutches for
different sets of gears. One clutch controls
first, third, fifth and seventh gears, while the
other clutch controls second, fourth and sixth.
This means that the next gear can be selected
beforehand and changing gear is simply a
question of one clutch disengaging as the
other engages, without the need to select
the gear in between. The result is a gearshift
which happens in just milliseconds and from
the driver’s seat there’s no perception of
interruption in the power. We’ve had plenty of
experience of the similar system in various
Audis and we’ve always thought it worked
better than the SMG system, good though it
undeniably is in the M cars.
 Unsurprisingly, the DCT box makes the M3
even faster: on the convertible, the 0-62 mph
time is reduced by 0.2 seconds while its greater
efficiency means fuel economy is improved
and CO2 emissions are decreased. Like the
other M models, the DCT cars come with the
Drivelogic system which allows you to finetune
the shift speed as desired, while an antirollback
system helps out during hill starts
and something called a Low Speed Assistant
makes the car tractable at traffic speeds.
You're looking at £54,655 for the convertible,
with the M DCT Gearbox a £2,590 option. |
