To get an idea of just how chillingly effective the new BMW M5 is, imagine yourself tooling along a smooth, lightly undulating Spanish back road at around 50mph. Ahead is a line of seven cars – none of which appears eager to overtake – and a straight stretch of asphalt dotted with broken white lines. You begin to calculate how many cars it's possible to pick off before the crest in the distance. Perhaps three, maybe four, conceivably five…
In the end the sums don't matter, because the new M5 has no trouble swallowing all seven cars in one full-throttle, third-gear lunge, and remarkably there's still a good couple of hundred yards before those broken white lines meld into an unbroken lane divider. To say the new M5 is fast is perhaps stating the obvious.
Truth is, we knew the new M5 would be a bullet in a straight line, what with 10 percent more power and a vast 30 percent more torque than its predecessor. The surprise is just how fast it is in real-world terms. I can't think of a four-door sedan, past or present, offering such potent yet openly accessible performance.
Being the first M5 to eschew naturally aspirated power in favor of turbocharging, it is all too easy to point to the engine and say it makes all the difference. But the more you drive it, the more familiar you become with all the different drive programs, and the more time you take in tailoring the damping to suit the road, then the more obvious it becomes that the new engine is but part of the bigger picture. This is an M5 like no other, and it's better in just about every respect.
Central to the technical advances that BMW has made is the decision to supplant the naturally aspirated 5.0-liter V10 of the previous model with a twin-turbocharged 4.4-liter V8. The 90-degree unit, which is mounted 20mm lower in the engine bay than standard 5-series powerplants, is a development of the engine used in the X6M. However, there are sufficient differences between the two units – including the cylinder head, internal architecture and the induction and exhaust systems – to lead BMW M officials to describe the M5's engine as being new.
Key among these changes is the adoption of Valvetronic fully variable inlet and exhaust timing. The M5 also receives unique intercoolers and a new pair of Honeywell turbochargers that run a nominal 0.9bar of boost – or 0.1bar lower than that of the X6M's engine. The pistons have also been modified for lower reciprocating mass, which has allowed BMW to up the ignition cut-out point to a reasonably high (by turbocharged engine standards) 7200rpm, although it's still a good 950rpm lower than that of the old naturally aspirated engine it replaces. There's also a new electronic management system that is claimed to have more computing power than any existing system used by a series production BMW engine.
At 552hp, the new engine delivers 51hp more than the old M5's naturally aspirated engine. However, peak power is now delivered 1750rpm lower in the range, at 6000rpm. More telling, though, is the torque. It peaks a substantial 153lb ft higher than before, at 501lb ft, but it can be tapped a telling 4600rpm earlier, at 1500rpm – or just 700rpm beyond idle. These figures mean that the new M5 continues a long tradition in which each iteration becomes more powerful and has more torque than the model it replaces.
A further technical highlight is the adoption of a new 7-speed, dual-clutch automatic gearbox as standard. The Getrag-engineered unit replaces the 7-speed sequential manual of the old model, offering both fully automatic and manual modes. It channels drive to the rear wheels through a newly developed version of M division's electronically operated Active M differential that's capable of providing continuously variable lock-up to each of the rear wheels, while revised gearbox and final drive ratios take full advantage of the diesel-like torque loadings. The new gearbox also adopts the automatic stop-start and brake energy recuperation features seen on other BMWs.
Visually, the M5 is distinguished from its 5-series siblings by a limited set of exterior styling changes. It's a fairly subtle makeover, but that, says BMW, is exactly what M5 customers want. Up front, a deeper bumper carries huge cooling ducts, along with a reworked grille, newly contoured hood and more heavily flared wheel arches.
Other differences include wider door sills, wider rear arches, a small trunklid spoiler and a new rear bumper. The most effective visual change, though, is reserved for the chassis. With a 27mm wider front track and 38mm narrower rear track than the standard 5-series sedan, the new M5 possesses an alluringly squat stance that is made all the better by a 25mm reduction in ride height and a set of 19in. alloy wheels. But with a drag coefficient of just 0.33, it's not as slippery as the old car.
The subtle approach continues inside. On top of the usual M5 accoutrements – M sports seats, trims, heavily bound leather-rimmed steering wheel and unique instruments – there's a reworked center console housing a stubby gearlever that is surrounded by a series of buttons. These include the all-important M button that allows the driver to alter the settings of the steering, throttle, gearbox and stability control as well as a button to alter the stiffness of the dampers in three settings: Comfort, Sport and Sport Plus.
It's a business-like driving environment crammed with all the latest in passive safety features, although it leans heavily on the regular 5-series sedan and ultimately lacks the flair that a car with such towering performance should surely offer. There's an on-board computer, for example, but unlike rivals it doesn't offer a g-meter even as an option. No such concerns about its practicality, though. With a 74mm longer wheelbase than its predecessor, the M5 now offers more rear seat accommodation than before. And with 18.4 cubic feet of luggage capacity, it matches the old model for load-hauling ability.