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The 330d may not be the most powerful model in the revised 3 Series range, but it still packs a serious punch. The 3.0l turbo-diesel engine's 383lb/ft of torque is certainly major twisting action by any sensible measure. With that in mind, the Dynamic Stability Control system is extremely welcome.
In default mode, the traction control part of the system is a little intrusive, quelling torque to the rear wheels even during routine driving. That probably reflects the fact BMW no longer fits limited slip differentials to its mainstream models. Given the torque on offer, it's therefore terribly easy to break traction with a single wheel. However, BMW has catered for driving enthusiasts by making the system fully switchable. Should you wish to light up the rears, you can turn off the traction control.
Further features within the stability control system include brake drying, which occasionally primes the rotors to reduce moisture and improve initial responsiveness in wet conditions, brake fade compensation which basically does what is says on the tin, and brake pretensioning.
The new E90 also sports BMW's latest Servotronic electric steering rack. It certainly makes maneuvering the car at parking speeds a cinch but it does rather undermine mechanical feedback. Genuine steering feel is sadly not part of the modern BMW experience. Complementing the stability and traction control systems, the E90 packs six airbags, anti-whiplash head restraints and LED brake lights.
With the overhauled E90, BMW is sticking to its guns regarding run-flat tyres. You can read about our thoughts on the ride quality. Suffice to say that in safety terms there are clear benefits. Sudden loss of pressure is much less dangerous with run-flat technology. Of course, the super-stiff sidewalls can serve to mask the symptoms of pressure loss, so BMW includes a system that cleverly detects any fall off in pressure by comparing the rolling radius of the tyres when the car is on the move.
Of course, many of these features operate invisibly to the driver. Only when they stop operating will you really notice what an important difference they make. More central to the 330d's immediate driving characteristics is the six-speed automatic gearbox. It's a multi-mode box and includes a Standard automatic mode for daily driving and a Sport automatic mode that's a little more keen to kick down under acceleration and hold onto gears higher up the rev range. Finally, the box supports manual gear changes courtesy of both the gear selector in the centre console and a pair of paddles on the steering wheel.
You pull the paddles for upshifts and push for downshifts. They're mounted on the steering wheel and so turn with it rather than being fixed. That's fine most of the time but can be a little problematical in tight corners requiring extreme steering inputs. However, the 330d does benefit from a fairly quick steering rack, removing the need to take your hands off the steering wheel in all but the tightest hairpins.
Overall, the box complements the drivetrain extremely well. The engine is enormously zingy and free revving for a diesel powerplant and the ability to zip up and down the ratios courtesy of the paddle shifters gives the car a very sporty and contemporary feel. The torque converter also locks up nice and early, too, which only adds to the athletic driving vibe. For sure, hardcore enthusiasts will perhaps find the system a little laggy and uninvolving. Even in M Sport trim, the 330d isn't the sort of car you'd take for a thrash early on a Sunday morning. But for most drivers it's both fun and efficient.
Speaking of efficiency, this car will return consumption numbers that utterly belie its sports scar humbling performance. When it comes to fuel efficiency, of course, every little helps and BMW more than any other manufacturer pays enormous attention to detail. The Efficient Dynamics package in the 330d includes Brake Energy Regeneration, an electric steering rack that reduces load on the engine by doing away with a pully-driven hydraulic pump and what BMW calls its Intelligent Alternator Control.
Needless to say, however, it's the 330d's modern diesel engine that contributes most to the car's impressive efficiency. BMW officially rates the 330d Auto at 45.6mpg combined and 54.3mpg on the extra urban cycle. Real world returns will vary depending on your driving style. In our hands, consumption was in the low 30s, but then we were - how shall we put it - enjoying the car's full potential. Exercise just a little restraint and 50mpg on long motorway journeys is easily achievable. With a fuel capacity of over 60 litres, that puts the car's operational range well beyond 700 miles. CO2 emissions, for the record, are just 152g/km, placing the 330d in band G for road tax rates. In 2009-10 that attracts a fee of £150, rising to £155 thereafter.
With the full iDrive system comes an upgraded parking assist feature. The car is plastered with sensors front and rear allowing a detailed picture of parking hazards to be rendered on the main iDrive display. It's a graphical representation rather than a video-based system and uses colour coding to emphasise the proximity of obstacles.
If there's one area we'd like to see improved for the next 3 Series, it's interior ambience. That's not to say the E90 feels cheap or shoddy inside. But it does lack the sheer density and sense of material well being of an Audi cabin, for instance. For that matter, wind back the clock to the 1980s and you'll see what a really well-made BMW interior looks and feels like. The quality of leather alone from that period shames the artificial-feeling hide BMW currently uses.
Nevertheless, the 330d M Sport is an extremely low-stress driving tool. The revised 3.0l diesel engine smoothes out the few remaining rough edges from the previous car's power delivery. On the move, it's an enormously refined and pleasant engine to use, even if it falls well short of the sonorous petrol 330i in terms of soaring soundtrack.
The M Sport chassis settings are also an extremely well judged balance between comfort and body control. We remain sceptical about BMW's continued use of run flat tyres. But there's no arguing with the fact that the revised E90 is a clear step forward over the original model when it comes to suppressing the little fidgets and thumps that have characterised run flat ride quality. The downside to run-flats on the latest Three are very minimal indeed.
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