BMW will launch its most potent 3 Series model this side of an M3 yet when the new M340i xDrive arrives next year. Powered by a 374hp straight-six, the car will hit 62mph in 4.4 seconds, which, if you want proof of progress (or, perhaps more appropriately, the effectiveness of all-wheel drive), makes it four tenths quicker to the mark than the V8-engined E92 M3 - you know, the one that felt monstrously fast only a few years back.
Its engine is the same 3.0-litre unit used in the M140i and M240i, but its output has been cranked to new heights for the larger 3 Series. BMW's engineers have asked more of the TwinScroll turbocharging system and upped its fuel injection pressure to 350 bar. There's also a new compact steel exhaust manifold and reduced mass moment of inertia to help the blower spin up faster.
BMW says the result is sharpened throttle response, more explosive performance through the rev-range and better overall efficiency. Torque now peaks at 369lb ft, helping the M340i to hit 62mph half a second earlier than the previous quickest non-M3 3 Series, the 340i (of the now discontinued F-generation) - although, again, some of the gains made in away-from-the-line performance can be attributed to the standard fitment of xDrive.
Ahead of its debut at LA later this month, European press releases make no mention of the RWD version that's to be offered in the US - a fact which might potentially displease the manufacturer's hardcore fan base on this side of the Atlantic - but BMW will be well aware that both significant rivals, the Audi S4 and Mercedes-AMG C43, use AWD as a distinguishing feature of their top-tier trim levels.
BMW does, however, reiterate that its xDrive system has a definite rear bias, and has underlined the fact with the standard fitment of an M Sport differential at the back. This electronically controlled, fully variable locking system provides the rear wheels with a traction advantage so they can play the more significant role. Also standard is the use of an eight-speed Steptronic automatic transmission with shorter ratios in lower gears to enhance acceleration.
Since this isn't a full-blown M model but an M-fettled one, the M340is uses the base of the new G20-generation 3 Series in largely unchanged form. It incorporates a double-joint spring strut front axle and a five-arm rear axle, and sits 10mm closer to the ground on M Sport suspension and bespoke damper settings. You can (read: should) opt for BMW's adaptive suspension with electronically controlled dampers as an option. There's also a variable steering option, but experience suggests this one might be less desirable. Throw in bigger brakes with four piston calipers and 348mm discs at the front, along with single piston floating calipers and 345mm discs at the rear and you have yourself one very well-equipped 3 Series.
Since the M340i sits among the regular model line-up, it does without muscle flexing features like flared arches. Instead, it signals its ranking with some extra aerodynamic features on the front bumper, a few M badges and some grey metallic trim outside. Inside, the subtle theme continues with M seats trimmed in sensatec (a synthetic leather) and Alcantara, a leather-wrapped M steering wheel and some M badges. Other than that, it's regular 3 Series.
Although as yet unconfirmed, we can expect the M340i to be followed by a Touring version and also an M440i for the two-door line-up. When these cars reach roads, they'll only remain the top models of their ranges for about a year as the red-blooded M models are due in 2020 using a substantially more potent version of its 3.0-litre motor. Consequently, you can expect the next gen M3 to produce around 100hp more than its half sibling. But don't let that put you off. Given its usability bandwidth and lower unit cost, the M340i might yet prove the pick of the range.