We Compared BMW M2 Engines, And The Efficiency Crown Goes To…

When discussing the efficiency of performance cars, there’s more at play than just their average fuel consumption. The specific power outputs of their engines play a significant role here, because it’s an indication of the potential locked up in that chunk of machined aluminium, steel and plastic. It also highlights how effectively such an engine converts petrol into power, noise and tyre smoke – as indicated by its specific power output (measured in kW/litre). So which one of the two engines to grace the BMW M2 is the most efficient?

BMW M2 (2016-2018)

This was the first iteration of the M2 to reach our shores, and, like its 1-Series M Coupé ancestor, used an engine which was derived from a normal, series-production BMW engine. In the M2’s case, it used an extensively modified variant of the N55 single-turbo engine family, which first appeared in 2009.

This engine was quite different from its more-modest siblings, however, with improved lubrication- and cooling systems, strengthened internal components, and much more aggressive tuning. In the M2, it produced 272 kW and 465 Nm (500 Nm on overboost), and was available with a choice between 6-speed manual or 7-speed dual-clutch automatic (M-DCT) gearboxes.

Related: We were besotted with the M2 right from the start, as illustrated in our first drive review.

Specific power output91 kW/litre

Average fuel consumption - combined cycle (manufacturer’s claim with M-DCT gearbox):7.9 ℓ/100 km

Estimated fuel range:671 km

BMW M2 Competition (2018-on)

In contrast to the earlier M2, the Competition (which succeeded the older car) had a bespoke engine – albeit still based on the N55 architecture. This engine is known as the S55, and first appeared in the F80/F82 M3 and M4 (in a higher state of tune), as a very extensive reworking of the N55 base design. Key differences include a closed-deck block, reinforced and lightened internal components, a twin-turbo arrangement, and revised intercoolers.

For duty in the M2 Competition, this S55 engine was detuned quite radically, and outputs peak at 302 kW and 550 Nm – considerably more than the older M2 managed, but a lot less than even the lowest-powered M3 version. The difference in straight-line acceleration isn’t as massive as you’d imagine in spite of that extra power, though, because BMW claims 0 – 100 km/h sprint time improvements of only 0.1 seconds over the non-Competition M2s, for both manual- and DCT-equipped M2 Competition variants. This is likely due to traction constraints, as either M2 is more than capable of keeping the rear tyres smoking well into third gear.

Related: Watch our video review of the M2 Competition here. It’s not for the faint-hearted.

Specific power output101 kW/litre

Average fuel consumption - combined cycle (manufacturer’s claim with M-DCT gearbox):9.1 ℓ/100 km

Estimated fuel range:571 km

Verdict:

There’s no doubt that the M2 Competition’s engine is more effective at extracting power and torque from its 3.0-litre displacement. The higher-tech engine can handle higher turbo boost pressure levels, which liberates more power – but it also means that the newer S55 engine in the Competition has to drink a fair bit more.

Furthermore, the Competition features an uprated cooling system and a bunch of extra turbo plumbing, all of which add about 55 kg to the older M2’s kerb weight. This, combined with its higher power output, means that the M2 Competition is noticeably thirstier than its predecessor, with more than a litre difference in claimed consumption figures between the older car and the latest one. As a result, the (slightly) slower, older "normal" M2 takes the efficiency crown from its M2 Competition successor.

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