Set to go on sale across North America in August 2012, the new model is, as tradition dictates, based on the latest 5-series. But don't think of the new four-door performance saloon simply as a warmed-over version of BMW's midrange model. As project leader Siegfried Friedmann reveals, “The new M5 shares just 20 percent of its components with the 5-series.” The remaining 80 percent is claimed to be unique.
The new M5 is bigger than ever before, putting on 55 millimeters in length and 46 millimeters in width over its direct predecessor. Some 19,331 examples were produced between 2004 and 2010. However, height has dropped by 13 millimeters. It also rides on a wheelbase that has grown by 74 millimeters and runs front and rear tracks that are up by 27 millimeters over the standard 5-series up front and down by 38 millimeters at the rear--the latter part of a complete chassis upgrade that sees the latest M car adopt a vastly different geometry to its more conservative four-door sibling.
Central to the technical advances is a decision to supplant the naturally aspirated 5.0-liter V10 engine of the previous M5 with a twin-turbocharged 4.4-liter V8 running the latest in piezo-guided direct injection. The 90-degree unit, which is mounted 20 millimeters lower in the engine bay than standard 5-series powerplants, is a development of the similarly configured engine used in the X6M, complete with its cross-bank induction system. However, there are sufficient differences between the two engines to lead BMW M officials to describe the M5's engine as being new. “They use the same block and crank. They are the only common parts. The induction, cylinder head, internal architecture and exhaust system are unique,” says Friedmann. It's not the truck engine many suspected, then.
Key among the changes is the adoption of Valvetronic, which provides fully variable inlet and exhaust timing while enabling shorter injection cycles for what Friedmann describes as added throttle response. The M5 also receives unique intercoolers and a pair of Honeywell turbochargers that run a nominal 0.9 bar of boost, or 0.1 lower than that of the X6M's engine. The pistons also were modified for lower reciprocating masses, something that allowed BMW to up the ignition cut-out point to a reasonably high by turbocharged-engine standards-- 7,500 rpm. There's also a new electronic management system that boasts more computing power than any existing system used by a series-production BMW engine.
Assembled at BMW's specialty engine workshop in Munich, the new forced-induction powerplant--the first of its kind to ever find its way into an M5--delivers 51 hp more than the old naturally aspirated engine at 552 hp. However, the power is now delivered 1,750 rpm lower in the rev range, at 6,000 rpm. More telling, though, is the torque. It peaks a substantial 153 lb-ft higher than before, at 501 lb-ft, but can be tapped some 4,600 rpm earlier at 1,500 rpm--or just 700 rpm beyond the engine's nominal idle. These figures see the new M5 continue a long tradition in which each iteration has successively become more powerful while boasting more torque than the model it replaces.
A further technical highlight of the new M5 is the adoption of a new seven-speed dual-clutch gearbox as standard. Essentially the same unit used in the M3, the Getrag-engineered unit replaces the seven-speed sequential manual of the old model. Running a unique set of ratios, including a very short 4.80:1 first and a heavily overdriven 0.671:1 seventh gear, it channels drive to the rear wheels through a newly developed version of the BMW M division's electronically operated Active M differential, capable of providing continuously variable lockup to each of the rear wheels and imbued with a 3.15:1 final drive.
In a word, rapid. It might weigh 4,114 pounds, 88 pounds more than its predecessor, but in real-world terms, the M5 is considerably faster than the car it replaces by dent of its more accessible performance. BMW claims 0 to 62 mph in 4.4 seconds, bettering the old model by 0.3 second up the strip. But I, for one, won't be surprised to see independent tests better this figure by a considerable margin.
It certainly feels faster. Its superb traction, heroic acceleration, rifle action gear change and ability to sustain high speeds on roads that would have worried the old M5 puts it on a higher performance plane than its predecessor. How does 50 to 75 mph in 3.7 seconds grab you? Top speed is, like all M cars, limited to 155 mph. However, an optional M Drivers Package bumps it up to a limited 190 mph--a figure BMW says its standard Michelin Pilot Super Sport tires are rated to.
So it is fast, fast enough to be a real threat to your license, so addictive is its performance and the deep thrum of its engine under full load. But what really distinguishes the new M5 from every M5 before it is the enormous flexibility of its power delivery. Bury the throttle at anything beyond 1,500 rpm--the point where peak torque is developed--and it surges forward with immense force, seemingly in any gear. Given the heady output, the tractability at low revs is quite staggering. It's a vastly different driving experience from the old M5, which required a good 4, 000 rpm before its engine would begin to deliver anywhere near the same vigor.
Driving the old M5 was always an event. But its performance relied heavily on your level of commitment to extract it. This new model is, for the most part, even more thrilling from behind the wheel. Yet it doesn't ask for any special favors on the part of the driver. Its performance, molded in no uncertain terms by its new engine's mountain of torque, is omnipresent. Overtaking is truly effortless, helped by the effectiveness of the new seven-speed dual-clutch gearbox. I'm not sure how BMW has done it, but the shifts are race-car quick, accompanied on full-throttle upshifts by an alluring bark of exhaust and a hearty blip on downshifts.
Still, the added flexibility while making the new M5 a more welcome everyday proposition does have its drawbacks. Chief among these is a curious lack of crescendo in its delivery. Because the torque is developed across such a wide range of revs, the engine doesn't feel much stronger at 6,000 rpm--the point where peak power arrives--than it does down low. The shove is colossal, but it is also oddly constant. Among the many delights of the naturally aspirated engine used in the old M5 was the way its intensity grew in line with the number of revs it was asked to carry. The new turbocharged engine is clearly more user-friendly but has nowhere near the same character. And despite running a relatively high 10.1:1 compression ratio and the latest evolution of BMW's Valvetronic system, it doesn't possess the same rabid throttle response.
The best part of the new M5, though, is not its outright pace but its overall agility. The overall feel is determined largely by the damper mode chosen by the driver: comfort, sport and sport-plus. A further factor in the new M5's dynamic ability is just how willing the driver is to alter the stability-control setting, which offers three settings: default, MDM (M Driver Mode) and completely switched--the latter of which requires the button to be depressed for three seconds.
In default mode, there's a lot of intervention from the dynamic stability control, which clearly was calibrated to provide a wide safety net and allow what Friedmann describes as “even the modestly skilled to take big liberties without coming to grief.” Switch it into M Driver's Mode, though, and the handling instantly becomes much more fluid in nature. I worried the big engine and all of its ancillaries might make for a nose-heavy cornering feel, but I was wrong. The new M5 feels wonderfully balanced--more neutral, in fact, than the car it replaces. Grip from standard 265/40ZR-19 front and 295/35ZR-19 rear tires is immense, but with all of that torque on offer the M5 is a willing sideways companion when you switch the dynamic stability control off.
The aluminum intensive chassis--with its new double-wishbone front suspension and heavily modified multilink rear end bolted directly to the body rather than braced with bushing as on the standard 5-series--offers superb body control. There is a moderate degree of lean as you guide the M5 into corners, but it actions are wonderfully progressive thanks to terrific damping that ensures any movement is retained within a tightly dictated range. Where it really impresses is in its ability to settle quickly when faced with nasty crests and undulations. There is sufficient give to ensure it doesn't fight the road, choosing instead to work with the lay of the bitumen.
There's also an impressive level of suppleness thanks to inclusion of variable damping that serves up three levels of stiffness--comfort, sport and sport-plus. Despite the obvious lack of compliancy in the standard tires, the overall ride quality is outstanding. Even in the most extreme sport-plus mode, the new underpinnings manage to retain a good deal of composure, seldom allowing anything more than a sharp ripple to upset progress. In this respect, it's much calmer and more relaxed as speeds increase than its predecessor.
It's the steering that slightly disappoints. The speed-sensitive hydraulic steering, geared at 2.7 turns lock-to-lock, is an improvement on the electromechanical arrangement used by standard 5-series models, offering a more convincing feel and greater levels of feedback. But it possesses a lifeless feel around the straight ahead. It's a pity because, once you've negotiated this tough spot, it's is much more alert. The weighting varies.
Are you kidding--yes! I don't care how, just make sure you sample the new M5 in one way or the other. It is in many respects a landmark car, one that's going to have the fast-car competition--Audi, Cadillac, Jaguar, Mercedes-Benz and Maserati, among them--scratching their heads as they attempt to come up with a reply.
The sheer potency and accessibility of the new turbocharged engine alleviates any lingering doubts about BMW's M division's decision to turn a 25-year tradition of naturally aspirated engines on its head. The question that really needs to be asked is, why did it take so long? What marks the new M car as something really special, though, is its superb combination of agility, ride and refinement. With a 21-gallon fuel tank and combined-cycle fuel consumption of 23.7 mpg (U.S.), it is not only the new muscle car of choice but also the perfect cross-continent express
