The BMW M140i Performance Edition (PE) comes in two distinct flavours.
The vast majority (45 out of 60) are fitted with a ZF eight-speed automatic and bar a fruitier exhaust score only cosmetic upgrades. For the tiny percentage of customers who prefer to shift their own gears (only 6 per cent of M140i buyers choose manual), the other 15 examples use a six-speed manual, but also benefit from a proper mechanical limited-slip diff from the M Performance parts range.
So which is best? Does the manual add a crucial layer of involvement? Can you even notice the effects of the limited-slip diff? To answer these questions BMW kindly lent us its automatic PE for a back-to-back test. Let’s begin by examining the traits common to both cars.
The B58 3.0-litre turbo six is an absolute powerhouse; we’ll go into more detail about this new engine in a future update, but suffice to say it has one of the widest powerbands around and a level of performance that’s borderline excessive for the public road.
As the only rear-drive challenger in the hot hatch segment, the M140i offers a unique driving experience that its front- and all-wheel drive rivals can’t match. It’s not without flaws: the brakes are a bit wooden and the suspension lacks both a little compliance and travel resulting in a jittery ride over rippled surfaces and the car hopping over bumps at speed, particularly at the rear.
But these slight shortcomings fade into insignificance when compared to the positives. Despite relatively narrow tyres (225/35 front; 245/30 rear) there’s ample grip, more than is initially apparent, but not so much that it’s impossible to adjust the car’s attitude at relatively sane speeds.
Indeed, driving the M140i PE back-to-back with the latest M4 Competition is illuminating. The M4 is clearly the more serious performance machine, but with pace dictated by road regulations and common sense, the M140i is working harder to achieve that pace and thus offers a more engaging drive.
It’s also the easier car to drive quickly. The M4 offers more power, grip and traction, but the corollary to this is an edgier balance if limits are exceeded; the M140i slides earlier but its movements are more clearly telegraphed – it can be driven extremely hard with confidence.
Paradoxically, its Sports ESP setting is also more lenient, subtly trimming your excesses rather than stealing power away. There’s a strong case to be made that the M140i is the most enjoyable driver’s car BMW currently offers, which makes the fact the next-generation will switch to front-wheel drive all the more upsetting.
The limited-slip diff really should be standard fit, though. It doesn’t make the difference it once did as BMW’s faux-LSD technology, which brakes the spinning inside wheel to transfer torque to the loaded outside wheel, has improved, but the mechanical diff still markedly improves traction and predictability, particularly in slippery conditions.
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With the B58 engine now producing 500Nm from 1520rpm, accelerating hard in the standard car frequently starts a fight with the electronics as the grunt is shuffled from wheel to wheel. More often than not, the LSD-equipped PE just hooks up and goes or smoothly transitions into oversteer if traction is lost.
It also allows the car to be steered on the throttle, a sensation that never gets old. Given only the manual is equipped with an LSD the PE purchasing decision is a no-brainer, however, manual vs auto is a little more complex.
Like for like, without exception the MOTOR crew would choose an automatic M140i; simply put, the manual is okay, whereas the auto is exceptional and feels a better match for the engine.
It also allows you to concentrate on working the excellent chassis harder and, with eight closely stacked gears to choose from, makes the car even quicker. With M140i pricing being cut to $59,990, we’d buy the auto and spend the $4800 saved on that LSD.
Fuel this month: 11.65L/100KM
Distance this month: 1009KM
Liked: Realising just how good this car is
Disliked: Ideal spec doesn’t exist
Favourite moment: Stalking the M4 on a twisty road