Why Is the F90 M5 So Fast?

Blistering is one way to describe the current BMW M5 and M5 Competition. Although many spoke out against the advent of an all-wheel drive M car, the F90 M5 was quick to win over the masses as soon as the first real-world performance measurements came back, with zero-to-60 times that defy expectations—and physics—for an executive mid-size sedan that tips the scales at well over two tons. So fast are the M5 and M5 Competition, that at least a few have speculated that the S63B44T4 V8 beneath the hood, which is force-fed at over 25 PSI, may be more powerful than advertised.

There is certainly something more captivating about the F90 M5 than the previous F10, and the selectable M xDrive system has a lot to do with it. While the previous F10 is known for its propensity to spin the rear wheels with just the slightest bit of throttle application under yaw, the F90 M5 grapples with the pavement with all four tires when the twin-scroll turbo hot V8 spools up, allowing it to rocket up to highway speeds and beyond at a pace that’s not far off the latest Porsche 911 Turbo and Turbo S.

Even with M xDrive allowing the latest M5 to make full use of its manufacturer advertised power and torque, there remained suspicion that the power plant beneath the hood was perhaps significantly more potent than BMW’s stated figures. Car and Driver was in the camp of doubters, and recently put an M5 Competition on an all-wheel drive dyno for testing.

To negate the potentiality of the intelligent M xDrive system to modulate torque, the test was run in 6th gear, which is a direct-drive 1:1 ratio in the M5 Competition. Depending on how familiar you may be with BMW’s reputation for underrating its power plants, the real-world figures for the S63B44T4 may surprise you: Advertised as developing 617 horsepower at precisely 6,000 rpm and 553 pound-feet of torque from 1,800 to 5,860, the factory-unmodified F90 M5 Competition tested by Car and Driver on a Dynojet all-wheel drive dyno put down a staggering 617 horsepower near the advertised peak, while a consistent wall of torque peaked at 606 pound-feet.

Accounting for drivetrain loss, which is supposedly shrinking with each new generation of automobile, the numbers indicate that the M5’s V8 is developing a healthy bit more power than is officially stated, perhaps approaching a lofted threshold of nearly 700 horsepower. BMW advertises the standard F90 M5 as hitting 60 from a standstill in a mere 3.1 seconds, while testing performed by automotive news media outlets has revealed a figure comfortably within the high two-second range, while the Competition model is even quicker.

The quarter-mile comes and goes in eleven seconds or less for either current M5 model, and when taken into account with a sub three-second zero-to-60 time, BMW’s first M car with xDrive suddenly finds itself in a performance realm dominated by significantly more expensive cars with fewer seats, fewer doors, and no room for a set of golf clubs—let alone four. Long term BMW fans have consistently appreciated all generations of the M5 as veritable wolves and in sheep’s garb, but the statement has never been more true than with the current M5 and M5 Competition, which combine all-weather performance with an ability to leave the vast majority of traffic in the dust whenever the S63 M V8 is called upon.—Alex Tock

[Photos courtesy BMW AG.]

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