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2020 BMW M340i xDrive review

The next M3’s junior brother is a serious performance saloon in its own right.
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It’s only a couple of generations since a typical BMW 3 Series was more likely to come with a six-cylinder engine than a four-pot, and the mighty M3 was still packing a glorious, naturally aspirated V8. No longer.

The new 2020 BMW M340i is the first petrol G20 with more than four plug leads, and the only other six-cylinder in the line-up will be the M3 that this car understudies for.

These days, it is easier to count the BMWs that don’t have M badges than the ones that do, yet despite being the junior version (and an ‘M Performance’ model rather than a pure-blooded single-integer M-car), the M340i has brawn aplenty.

It uses a single-turbo version of BMW’s B58 engine making 275kW when fitted with an exhaust particulate filter, but 284kW without one.

And, as my first drive was in the States, I got to experience the modest increase in ponies; a total that puts it close to the launch spec of the last-gen M3 and M4.

We’ve already driven a prototype version of the M340i on the Portimão track in Portugal, and the good news is that in rural Michigan the impressions stay overwhelmingly positive, driving a route that included both interstate and frost-broken backroads with some fairground crests and cambers.

BMW has had several M-badged misses in recent years, but the M340i isn’t one of them.

Drive heads to the road through the familiar eight-speed ZF auto, and my US test car was also a rear-driver – the rest of the world will get xDrive AWD as standard.

On BMW’s American numbers this saves 54kg in weight, but adds 0.2 seconds to the car’s official 0–60mph (0–97km/h) time, taking it from 4.2 to 4.4 seconds.

The powertrain is truly special, the M340i combining low-speed refinement with high-intensity zing better than pretty much anything else.

The motor has deep lungs when asked to make gentle progress, and the transmission shifts intelligently to make use of the prodigious quantity of torque.

But excitement is never more than a stamped throttle away, the gearbox shedding ratios near instantly and the engine pulling with a hunger for the upper reaches of the digital tacho.

Peak power comes at 5800rpm, but the motor carries on with no diminution of enthusiasm to the 6500rpm limiter.

Despite the potency of the powertrain, and the motor’s ability to summon its peak 500Nm from just 1800rpm, the lack of driven wheels on my rear-drive tester was rarely noticeable and never an issue. The Michelin Pilot 4 S tyres find huge grip, but also give up gradually as their lateral limits approach.

Pushed hard in tighter corners, the rear-drive M340i felt unsurprisingly rear-driven (as we discovered the prototype xDrive does on track), and with the stability control switched to its more permissive Sport setting, the back axle can easily be persuaded to nudge into power oversteer. But the clever torque-biasing rear differential means that it never feels snappy – even with the stability fully off, it stays progressive and predictable.

Under less intense progress the differential is still working out, especially in Sport and Sport Plus modes, helping turn the car by juggling effort between the rear wheels.

As we know, the considerably brawnier M3 will share the M5 and M6’s option of a pure rear-drive mode, the 340i’s already high aptitude for going sideways suggests it will be an absolute drift beast.

Raw adhesion is only a part of the dynamic story, and the M340i’s steering is also a welcome return to form when compared to some of the low-feel helms the brand has inflicted in recent years. The weighting of the electrical assistance varies in the car’s different dynamic modes, with the softest Comfort feeling the most natural.

But there is both a decent sense of connection to the front wheels and much more of the chatty feedback that Munich’s engineers previously tried to filter out as unwanted ‘noise’.

You can feel changes in road texture now, and better sense when the front tyres are starting to run short of grip. No, it’s not as good as an E46 330i – or even an E90 335i – but it’s heading in the right direction.

The M340i’s ride-handling compromise has been taken further to the right than is usual for BMW these days, with the suspension always on the firm side of comfortable. My test car was fitted with the optional adaptive dampers, with even the softest Comfort setting putting an edge onto bumps and ridges. Core body control is good, with the stiffness of the G20’s structure obvious in the discipline it shows when asked to tackle a rough road at speed.

But although the vertical motions are kept under tight control, occupants still get to experience pretty much all of them. Cruising speed refinement is good, though, at the expense of noise from ruts and expansion joints.

Then there’s the range-topping 3 Series’s static attributes, which are considerable. A subtle bodykit helps it to assert its superiority over lesser versions, looking particularly muscular from the rear (if you don’t object to the over-large exhaust finishers too much).

The cabin is brilliant, with beautifully rendered high-definition display screens, a huge range of driving position adjustment and high-quality materials everywhere.

The forthcoming M3 will be faster and likely better to drive at the limit, but it’s hard to imagine it will be a nicer place to spend time than its junior sister.

As for how it compares with the Audi S4 and Mercedes-AMG C43 – that’s a scrap to look forward to calling a verdict on.

NOTE: The M340i is now on sale in Australia, however press vehicle availability has been delayed until December. Watch for our full local review to come then.

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Engine: 2998cc, straight-six, turbocharged
Transmission: 8-speed automatic, rear-wheel drive
Power: 275kW @ 5500–6500rpm (284kW as tested)
Torque: 500Nm @ 1850–5000rpm
0–100km/h: 4.4sec (4.2 xDrive)
Top speed: 155mph (limited)
Weight: 1670kg [xDrive]
MPG: TBC
CO2: 160g/km [WLTP]
Price: $99,900