Wednesday, April 14, 2010
Courtesy of Edmunds Inside Line
Push the start button on the 2006 BMW M5 and there's a slight delay before the engine fires as if to hint at the complexity you're about to set in motion with your finger. And when all 10 cylinders burble to life they give new meaning to the words "performance sedan."
The engine, 5.0 liters of smooth-idling perfection, is capable of more than 8,000 rpm. It typifies the harmony at work in the M5: At idle its creamy smoothness belies its full capability. Like the rest of the car, it is what you want when you want it: relaxed and composed one minute, intense and aggressive the next. It is…balanced.
So throw out your preconceptions. Ignore logic. Forget what you think you know. Then engage the MDrive button and mash the throttle and the M5 will readjust your automotive sensibilities.
MDrive, as BMW calls it, changes the M5's character however its driver chooses. It can, at the push of a button, transform the car instantly from a comfortable and quick luxury sedan to a brilliantly balanced, insanely fast road weapon. Technically, you could set everything to change very little, if at all, but when used properly, it increases the M's power output from 400 to 500 horsepower, swaps its throttle response, shift speed and suspension damping to more aggressive settings and disables stability control. Think of MDrive as the M5's Jekyll and Hyde button.
Bump the M button, nudge the paddle, breathe the throttle and we're under way. All at once this is a different sedan from the one we parked last night. Last night it was comfortable, not soft but comfortable, shifted slowly (too slowly), and made some pretty good yank when we stepped on it. It was a banker's car. Or a doctor's car. Dr. Jekyll, perhaps.
Now it's different. Now it's sharp-edged and angry. Delay and hesitation are gone. Every action is met with a deliberate reaction. Throttle jabs in the first two gears will send you to the chiropractor. Expansion joints become speed bumps. Full throttle upshifts — even in a straight line — require countersteer correction. It is immediate. It demands respect. It is Mr. Hyde after a swirly and sugar buzz.
This personality engages serious drivers in ways others in its class never could. This is a car that takes braking, turning, accelerating and hauling passengers seriously.
An engine for the history books
From outside the car, the 5.0-liter V10's sound at idle is tinny and not at all pleasant. The harshness is the reverberation of high-energy exhaust pulses inside the long, stainless-steel manifolds. It's an ugly, abrasive sound uncommon in the world of production engines, where exhaust energy is almost always muffled by cast iron. It's also the sound of BMW's undiluted focus on performance.
Rated at 500 hp at 7,750 rpm and 383 pound-feet of torque at 6,100 rpm, the aluminum engine has a unique power delivery and its combination of sound and thrust are entirely out of place in a sedan. There's no surge of torque when the throttles are opened like in any of the current sports car engines making similar power. Rather, there's a linear wave of thrust that crescendos with an intake shriek which sounds genuinely pissed at its 8,250-rpm redline.
Much of the sound comes from the 10 individual throttle bodies swallowing air through the large plastic intake plenums that cover both banks of cylinders. But the throttles are only the beginning of the technology at work here. There's also VANOS variable valve timing infinitely adjusting the opening and closing of the four lightweight valves at each cylinder.
Other exotica? How about the 12.0:1 compression ratio, hollow camshafts and those ugly-sounding 22-inch exhaust headers. This is an expensive engine. But it makes power and stirs the soul in direct proportion to its cost.
SMG: Round three
A new seven-speed Sequential Manual Gearbox is assigned the duty of transmitting the V10's power to the tarmac and BMW tells us a six-speed manual transmission will be available in the fall of this year. The new SMG, unlike it predecessors, is the first BMW gearbox designed exclusively to operate as such. Designing it from the ground up as an SMG made it stronger and quicker-shifting than previous versions.
Drivers select from two operating modes: sequential or automatic. In sequential mode, gears are selected manually using the steering-wheel-mounted paddles or the shift lever. There are six programs to modify shift speed and clutch engagement in sequential mode. During downshifts in this mode, revs are matched to the selected gear. Requests for a downshift which would overrev the engine are ignored.
Automatic mode, from a user standpoint, is very similar to an automatic transmission in which shifts are made for you. Five shift programs are available in automatic mode and they're all quite slow.
In action it's a blessing and a curse. On its most aggressive setting it lacks subtlety to the point of feeling abusive. Full-throttle upshifts begin with a microscopic pause followed by a violent thud as torque reloads the drivetrain. They're loud, ugly and fast as hell, so be sure you mean it if you're going to do it.
Downshifts, when they're executed as requested, are heavenly. Rev matching is as computer precise as expected. But more often than not when driving hard, they're ignored. Timing downshifts to the predicted rate of deceleration is still not a task suited for street-car technology. We often had to work the downshift paddle two or three times before we got the desired gear.
A chassis dressed to thrill
Visually the M5 stands out from other 5 Series models with double-spoke 19-inch wheels, quad exhaust tips, quarter-panel vents and several minor body changes including a small trunk lid spoiler. It's a subtle freshening that will only be noticed by those keen enough to know it's an M car.
Underneath the M5's skin is a capable all-aluminum suspension design that's up to the task of harnessing this kind of power and weight (4,012 pounds). Conventional MacPherson struts up front and single lower control arms with two upper lateral links at each side make up the rear suspension.
Damping is electronically adjustable in one of three modes: "Comfort," "Normal" or "Sport" via BMW's Electronic Damping Control, which continues to adjust damping to suit road conditions within each mode. The ride, even in Comfort mode, is exceptionally well controlled. The Normal setting provides an aggressive ride and Sport is stiff enough to only be useful on a glass-smooth racetrack.
The M5's steering ratio is variable and quickens as the wheel is turned off center. Steering assist is also variable between two levels which are linked to the car's electronic damping modes. In Comfort mode more steering assist is available than in Normal or Sport modes. Steering feel is typical BMW, with sharp off-center response and a just-right soft spot on center so as not to feel nervous when cruising. It's an appropriate balance for a car like this.
Naturally, BMW's most advanced braking system graces the M5. Behind the 19-inch wheels are huge 14.7-inch front and 14.6-inch rear two-piece rotors bringing the big sedan to a stop. Surprisingly, there are no four-piston calipers hiding in the front wheels. Instead, BMW chose a far less sexy dual-piston sliding-caliper design.
Power is sent to the Continental SportContact2 tires through BMW's M Variable Differential Lock limited-slip rear differential. Torque is distributed evenly between the rear wheels when viscous fluid in the clutch-type differential is sheared by a difference in wheel speed. In action, it's a quick-reacting, natural-feeling torque distribution that spreads rubber on pavement like butter on toast.
Overall, with its combination of leather, satin aluminum or wood trim and iDrive, the M5's interior is a distinctly Bavarian balance of form and function. Because iDrive controls navigation, climate, stereo and communication settings, the dashboard is relatively uncluttered. Switches on the center console control engine output, suspension modes and all 11 SMG calibrations.
The optional 18-way adjustable heated seats in our test car were equipped with active backrest bolsters which move inward to brace the driver or passenger against cornering loads. They are a gimmicky feature that can distract at critical moments. Luckily they can be switched off. We'd make due with the standard heated seats which are only 16-way adjustable.
The thick-rimmed leather steering wheel is stitched with red and blue and serves as the perfect frame for the easy-to-read 200-mph speedometer and 9,000-rpm tachometer. There's also a head-up display which projects engine speed and gear selection into the lower portion of the windshield, but we could never find it at a glance.
How's it stack up?
This is a very different car from the Cadillac STS-V or Mercedes-Benz E55 AMG, its only obvious competitors. Both of those cars are powered by grunty, supercharged V8 engines that, when compared to the M5's high-revving V10, feel like they belong in a tractor. This unique power delivery endows the M5 with more edge and involves its driver more than a lower-revving engine.
The M5 is also faster than the Cadillac and on par with the E55 in virtually any contest of speed. Our test car plowed through the quarter-mile in 12.8 seconds at 115 mph — a full half-second quicker than the comparably priced Cadillac. It hit 60 in 4.8 seconds, slightly slower than BMW's claimed time of 4.5 seconds. Our test surface isn't known for its grip, and without the aid of launch control, which isn't available on U.S.-spec M5s, launching the car is a trial-and-error procedure.
Perhaps most impressive was the M5's 69.2-mph slalom speed, which trumps the Cadillac by exactly 4 mph — no small margin in this test. Surprisingly, it generated only 0.86g around the skid pad, a number that doesn't reflect its capability.
Braking distance from 60 mph was outstanding at only 112 feet — 10 feet shorter than the Cadillac. Pedal feel was initially solid and confidence inspiring, but we did notice very slight fade after five back-to-back stops.
Is it for you?
Learning the M5's nuances, the ins and outs of its various systems and its ridiculous number of adjustments, is a serious task. And it comes with a serious price. Our test car totaled $89,090 with options and the mandatory gas-guzzler tax.
The M5 is one hell of an advanced car and it will challenge anyone who approaches driving like a conventional enthusiast. Most of the time it's brilliant and more than capable of meeting its driver's requests for power, grip or comfort. But get lazy — leave the tranny in 7th gear then mash the throttle for a quick pass on a back road — and the SMG's brilliance fades as fast as the oncoming headlights loom. No amount of technology will save you from idiocy in manual mode.
The 2006 BMW M5 isn't just a sedan. And it isn't just a performance car. It's a new breed of machine that defies definition. It's a 500-hp four-door that's equal parts passion, performance and highfalutin utility. Like we said…balanced.