Miles Cook, Contributor
Scott Memmer, Contributor
There's a glass ceiling in the automotive world when it comes to what you get in relation to what you pay for. The BMW M5 is slammed up hard against that ceiling and we think paying more for any new car is a foolish waste of money. Put another way, spending more than the approximate 75 grand needed to acquire an M5 is where the law of diminishing return begins in terms of all things automotive.
Case in point when looking at the highest echelons of four-door super-luxury sedans: Why would anyone spend 200 or 300 bills on a car like a Bentley or a Rolls Royce when the M5 is so much better than anything at any price that it makes the car a screaming bargain in the process? It just ain't worth it and that's why we look at the M5 as the ultimate car of any type especially when you factor in what the M5 costs and what you get for that price.
Before we get into why the M5 is on the razor-sharp edge of this spectrum, a comprehensive overview of this amazing machine is clearly necessary. The first-ever V8 in any BMW M car, the M5's 5.0-liter (at 4941 cc, it's really a 4.9-liter) powerhouse is probably the most spectacular engine available in any car today. Based on the M62, 4.4-liter DOHC mill in the 282-horsepower 540i, the M5's engine is designated the S62.
While the basic architecture is similar, the M5's engine is entirely unique. Using the hot-rodders magic dust that's known as stroking, the M5's engine has an increased stroke from 82.7 millimeters to 89 (or in standard terms 3.50 inches). The M5's aluminum block is a specific casting. Its 94-millimeter (3.70-inch) cylinder bores are also slightly larger compared to 92 millimeters in the 540i. An increased stroke is the shortest path to more torque and the M5 delivers in 500 cubic-inch, American big-block V8-type portions.
The longer-stroke crank moves oil-cooled pistons specific to each cylinder bank. The cooling is achieved via two separate oil passages in the crankcase. Compression is 11:1 a full point higher than the 4.4-liter in the 540i.
The M5's engine oiling system is as exotic as the rest of the motor's innards. Sensitive to the high cornering ability the car is capable of achieving, engineers deemed that natural return of oil to the oil-pan sump would be inadequate during extreme cornering. Therefore, two scavenging pumps, one for each cylinder bank, are utilized. In normal driving, these pumps pick up oil from the rear of the engine and return it to the sump. During hard cornering (0.9g or more) the Dynamic Stability Control (DSC) system's lateral-g sensor switches magnetic valves to different pickup points at the outer side of the oil pan. This system remains active even if the driver switches off DSC. A thermal sensor monitors oil level and temperature and a warning appears in the "check control" display if the level falls below a certain point. Replacing the fuel-economy gauge found in many BMWs, the M5 has an oil-temperature gauge in the tach face. Additionally, oil is cooled by a coolant-oil heat exchanger, the first-ever application of this on a gasoline engine.
Moving up from the engine block, the M5's cylinder heads are also updated from the 540i with more efficient cross coolant flow and larger intake ports. Although the 35-millimeter intake and 30.5-millimeter exhaust valves are the same as the 540i, the M5 has more aggressive cam profiles, another element contributing to its prodigious power output.
On top of the massive amounts of torque supplied by the increased stroke and cylinder-head modifications, the S62 breathes like a wild fire fanned by a giant bellows. A special induction system takes air in at two points behind the front bumper, passes it through two intake silencers and into a pair of mass-air meters before heading into a carbon-fiber plenum on top of the DOHC cylinder heads. From there, air travels through 230-millimeter intake runners to the cylinders. The plenum and runners are attached to the throttle housings by a rubber/metal flange that separates the plenum from the engine itself, thereby keeping the air charge cooler before it goes into the cylinders.
Air going into the cylinders isn't through a single throttle body as it is on almost all automotive street engines, but rather through eight separate throttle butterflies that are controlled electronically when the driver presses the accelerator pedal. A separate throttle butterfly for each cylinder is usually found only on purpose-built racing engines. Previous M car inline sixes, like those in the M1, earlier M5 and M6, had a similar setup, but none of those were electronically actuated.
Of course, these separate 50-millimeter throttle butterflies are much closer to their respective cylinders than a single unit could ever be, so air flow lag times are eliminated and the engine ends up having much improved throttle response.
The fly-by-wire system operates thusly: The driver give commands with the accelerator pedal to two potentiometers which move each throttle butterfly operating in its own housing mounted directly at the intake ports. As the driver moves the gas pedal, the commands are calculated by the engine's computer processor and received by a DC servomotor between the cylinder banks. In turn, through a small gearbox, this motor drives a shaft that drives a link to each cylinder bank to rotate the throttle butterflies of that bank.
These two links rotate the throttle shafts, connecting via balljoints at cylinders 3 and 6. From these points, the other three throttle butterflies are opened and closed and the servomotor reacts to any pedal movement in a light-speed-like 120 milliseconds. The result is the driver perceives no lag time only instant throttle response. Furthermore, the M Driving Dynamics Control System, controlled by a switch on the dash, provides two settings for throttle response: normal and an even quicker sport mode. In addition, the throttle butterflies for cylinders 4 and 8 have their own feedback sensors to monitor operation. If a fault is recognized in the system, one of four limp-home modes allows operation of the car at speeds of up to 62 mph.
Besides the engine, oiling system, cylinder heads, intake system, and throttle control, there's yet more wizardry hidden under the bonnet of the heroic M5. The final piece of the M5's powerplant puzzle is Double VANOS steplessly variable valve timing. The VANOS acronym refers to variable cam control or variable valve timing (in German VAriable NOckenwellen Steuerung). Double VANOS is employed on a BMW V8 for the first time in the M5. It steplessly varies the timing of both intake and exhaust valves on both cylinder banks. While current BMW 2.5- and 2.8-liter inline sixes also have the Double system, the 4.4-liter V8 used in the 540i, 540iT, 740i/740iL and X5 have a Single VANOS system that only varies intake-valve timing. In addition to more low- and medium-speed torque output, the advantages of VANOS are numerous. Even before the car is moving, you get reduced unburned hydrocarbons during idling, smoother idling, internal EGR (exhaust gas recirculation) at low speeds for improved control of nitrogen oxides (NOx), quicker warmup of catalytic converters after cold start (thereby reducing emissions during this operational phase), and reduced combustion noise.
As with other BMW engines, the VANOS mechanisms are at the front of the cylinder heads. Dedicated oil pumps provide the 1450 psi of hydraulic pressure used to actuate VANOS with one per cylinder head. Furthermore, valve timing is varied over a range of a full 60 degrees in terms of crankshaft rotation, a wider adjustment range than on any other BMW engine.
The S62 also uses a unique Bosch Motronic engine control system dubbed the MSS 52. In addition to controlling basic engine functions, this processor oversees the electronic throttle system (including cruise control and DSC), the engine's g-sensitive lubrication system, the thermal oil-level sender, catalytic-converter protective functions, Double VANOS, a 7,000-rpm rev limiter, and the M Driving Dynamics Control which provides two settings for the throttle system and power steering.
The Motronic also administers a variable tachometer-warning zone that reminds the driver that a cold engine should not be driven hard. When the engine is first started, the "yellow" line indicated by orange LEDs begins at 4,000 rpm. As the engine warms up, the LEDs turn off to lift the limit in 500-rpm increments until the normal limit begins at 6,500 rpm. The actual redline is 7,000 rpm.
The result of all these cutting-edge mechanicals is no less than the world's most powerful four-door sedan as the M5 makes an even 400 horsepower at 6,600 rpm and 369 foot-pounds of torque at a low 3,800 rpm. There isn't a four-door car on earth that can touch it.
The M5 isn't available with an automatic transmission. Its Getrag six-speed is the same basic unit as found in the 540i, but with a strengthened self-adjusting clutch. With a stump-pulling 4.23:1 low gear, fifth is 1:1 and the overdriven sixth is 0.83. The final-drive ratio in the limited-slip rear differential is 2.81:1.
The M5's chassis is as equally dazzling as its drivetrain mechanicals. Mostly based on the 540i six-speed, the M5 has firmer shocks and springs and low-friction steel balljoints that replace rubber bushings at the outboard ends of the rear suspension's upper arms.
The quick-ratio power steering has a 14.7:1 overall ratio and M Servotronic power assist. Compared to the engine-speed-sensitive variable assist of lesser 5 Series cars, the M5's system varies power assist according to vehicle speed. The system is calibrated for a firm road feel and the recirculating-ball steering gear has an automatic pressure-point adjustment that eliminates free play in the straight-ahead position. The result is precision comparable to that of rack-and-pinion steering while retaining what BMW says is the superior suppression of road shocks offered by the recirculating-ball mechanism.
Put all this rather awe-inspiring technical prowess together and you get a driving experience that's on the same level: awe inspiring. An editor took our LeMans Blue test car home one evening and surmised this: "There are no superlatives to describe how close to perfect the M5 is for the serious driving enthusiast. Take everything ever uttered or written about a BMW, magnify it 10 times, and then apply it to this car."
Most of our staff felt the same way. On deserted stretches of lonely two-lane, the M5 is pure fantasy pulling up to and blasting through triple-digit speeds like a cheetah chasing down its prey. Massive amounts of big-block-style torque are available at any engine or vehicle speed, in any gear - remarkable for a motor barely displacing more than 300 cubic inches. It almost feels as if the faster you go, the harder the engine pushes you to license-endangering velocities.
Besides the warp-drive-like thrust of the M5's powerplant, its chassis dynamics are equally enthralling. Over twisty back roads and hairpin curves, the M5 is simply infallible in its ability to go, stop, turn and grip. Despite its hefty 4024-pound curb weight, the M5 is as much at home on a racetrack as it is in the valet-park at any city's most exclusive watering hole.
In fact one editor placed the M5's capabilities beyond some of the most sporting two-seaters, citing that it goes about its business "like nothing I've ever driven before, including a C5 Corvette, an Acura NSX and the often-rickety Dodge Viper."
Staffers who cycled in and out of the car also noticed another trait of the M5 so extreme that no other car we've ever driven comes close. It might even be somewhat of a bad thing at least in terms of the legal standing of one's driving record. The car is so competent that it lulled everyone who drove it into believing that 80 mph on a four-lane highway equates to a mellow Sunday drive puttering along like an old man. One editor related, "I literally had to force myself down to 65 mph (in a 55 zone) and set the cruise control to keep from getting arrested by the local gendarmes."
Although the M5's look is so subtle that most mistake it for a standard 540 or even a 528, we still had a blast playing head games with those who think they might've had a leg up on us in such cars as a Porsche 911 or a Corvette. One editor who had a particularly good time with snooty 911 drivers noted, "It's great (and a little weird) driving a sedan with leather seating, decadent luxury, satellite navigation and scads of other features while simultaneously seeing Porsche 911s on the road and thinking 'I'm faster than you. Your car ain't s--t.'"
Picking on unsuspecting Porsche drivers and pilots of other seemingly high-powered machinery aside, our M5 proved to be a bit fickle at the test track when it came to generating outright stellar quarter-mile times. It should be noted, though, that neither the car nor the driver was at fault. Rather, the track's somewhat greasy conditions contributed to slower-than-expected performance. But even though our mid 13-second quarter-mile times were a few tenths off the car's 13.3-13.2 second capabilities, the trap speeds clearly communicated that our car was as strong as any M5 that's been tested by anyone else. We recorded consistent speeds of 105 mph on our way to a best e.t. of 13.75 seconds at 105.7 mph. We also pedaled (and we do mean pedal in first and second gear) the M5 to 60 mph in 5.28 seconds. As expected, the M5 excelled in braking and skidpad testing, too, stopping from 60 mph in a scant 116 feet and circling our 200-foot diameter pad with .90 g of lateral grip. Top speed is electronically governed to 155 mph, but BMW has said that with no governor, the M5 would probably be good for up to 180 mph.
But hard test numbers tell only a fraction of what this car is all about. We see the M5 as a convergence of all the best a car can offer. It has performance on par or beyond that of a C5 Corvette or 911 combined with four doors, room for five, a real trunk with 11.1 cubic feet of carrying capacity and rock-solid build quality. One editor likened the M5 to a sports car with capacity to carry people and cargo. He further noted that, "Unless you're sold on a Boxster S or Corvette's looks, and if you've got the dough, the M5 makes a far more practical performance machine." In most ways the M5 is just about a perfect car.
But not quite. While the M5's flaws are just about exclusively confined to inside the car and none really have anything to do with how this Bimmer actually drives they are still notable and in some instances, almost annoying. A number of staffers thought the gauges were on the small side and the steering wheel rim also obscures the tops of them. Some drivers felt the DSC system was too intrusive during spirited driving shutting it off would cure that. A problem with all current BMWs: to shut off the HVAC fan you have to click the control switch numerous times. Other nitpicking could include an uncomfortable center armrest, control markings on the dash that are difficult to decipher, and the navigation system that takes too long to update your location when you're simply tracking the car's position on the map.
Otherwise, the interior is a model of comfort and civility. With 16-way heated power seats, everyone who drove the car was able to find an ideal setting to concentrate on piloting this rocket ship. One staffer was happily able to find a "perfect driving position with adjustable lumbar and a myriad of seating positions."
The only gripe related to driving the car concerns the clutch. One driver noted that at times it was "heavy with an abrupt engagement point that proved to be a hassle in traffic."
Sure, one can carp about such frivolities like clutch engagement, but we'd say that particular editor can take a long walk. The M5 is the world's finest sedan with stunning acceleration, eye-popping grip, anchor-imitating brakes, ballerina-like chassis dynamics, decadent luxury, and people-and-stuff moving practicality all rolled up into subtle but aggressive and purposeful-looking bodywork. At any price, this car, to take a page from a Jack Nicholson movie, is "as good as it gets."
System Score: 8.0
Components. Electronically, the system consists of an AM/FM/cassette radio fed into an in-dash video display. The system also includes a six-disc CD changer. The highlight of the system is a three-way array of speakers in the front doors a dinky 4-inch bass that sounds amazingly good, a 2-inch midrange driver, and a 1-inch dome tweeter tucked into an A-pillar enclosure. This is complemented by a pair of 6.5-inch mid-bass drivers along the back deck and a pair of tweeters in the rear doors. The system is nicely laid-out and perfectly positioned in the dash.
Performance. This is probably the best stereo I've heard in a BMW vehicle. The Bavarian-based manufacturer, which makes some of the best cars in the world, is frankly not noted for producing great sound systems. In fact, it's been lacking in this area for years. It was therefore a pleasure and a bit of a shock to turn this stereo on and hear such great sound coming from the speakers.
Almost every facet of this system is flawless. Saxophone, for instance, a very difficult instrument to produce accurately, sounds lush and warm on this system, and not boxy at all. Likewise female vocals, which really test a speaker's mettle. Midrange is detailed and refined, with great intricacy throughout. Bass, as my notes say, is "rich, deep, accurate and tight." This system actually sounds a little bottom-heavy, a rarity in any BMW. Highs are clean and linear, with just a slight harshness at higher volumes (most likely the amplifier's fault). Just a great sounding system in an awesome car.
Best Feature: Superb stereo imaging and voicing.
Worst Feature: Power amp slightly weaker than other cars in this class.
Conclusion. This is one of the few systems where I say, "I wish I had more time to listen to this one." Scott Memmer
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