BMW's Velvety New 550i Takes on Infiniti's Macho M56
A twisty road in Malibu beckons the 2011 BMW 550i and the 2011 Infiniti M56.
By Mike Mo*****llo, Road Test Editor | Published Dec 28, 2010
When it comes to respectability in the midsize sport sedan segment, all roads lead through BMW's 5 Series. It's been ruling this class for decades now, and for good reason. It has the uncanny ability to satisfy both driving enthusiasts and buyers who are simply looking for a luxury sedan with German cachet.
Now that the all-new twin-turbo 2011 BMW 550i is here, it was time to see just how well it stacks up against its newest competitors. But instead of going toe-to-toe with a classic European rival, we figured a match-up with the latest from Japan would be more interesting. For that we turned to the all-new 2011 Infiniti M56, a thoroughly redesigned sedan that is once again aiming for the Germans. It has all the makings of a worthy competitor, but how does it hold up on the road?
How They Stack Up
You wouldn't be the first person to mistake the new 5 Series for the 7 Series, or vice versa, their styling is so similar. The M56 was designed as a serious sport sedan, made even more so by the optional Sport package our test car was outfitted with.
Not surprisingly, the 2011 BMW 550i and 2011 Infiniti M56 have plenty of similarities. Both are rear-drive sedans powered by sizable V8s. In this case, both are hooked to automatic transmissions, a seven-speed in the Infiniti and an eight-speed in the BMW.
To make sure no one whines about "stacking the deck" in one car's favor, both the 550i and the M56 were outfitted with Sport packages. The Infiniti's $3,650 option adds a stiffer suspension with upgraded springs and shocks, larger brakes, Bridgestone Potenza RE050A summer performance tires on 20-inch alloy wheels, four-wheel active steer, paddle shifters, sport seats and a unique steering wheel and shift knob.
The BMW 550i had the benefit of both a Dynamic Handling package, which includes electronic damping control, active roll stabilization (active antiroll bars) and Adaptive Drive (allowing for specific chassis/drivetrain settings) for $2,700, as well as a $2,200 Sport package, which adds a sportier leather steering wheel, multicontour seats, special exterior trim, an increased top speed (limited to 150 mph) and — surprisingly — 19-inch Goodyear Excellence run-flat all-season tires.
Technology and luxury abound in these cars, the kind of niceties that make your drive safer (the BMW's standard adaptive cornering headlights) and more relaxing (Infiniti's standard heated and cooled front seats). Differences come in the form of which features each manufacturer supplies standard, and which ones they make you pay extra for — as an example, you can get those adaptive headlights on the Infiniti, but it'll cost $3,000 as part of the Technology package; conversely, neither heated nor cooled front seats come standard in the BMW — heated seats cost $500 (or could be part of a package), while seat cooling tacks on another $1,950-$2,950 depending on the package.
As you might have guessed, these are expensive sedans. The M56 starts at $58,765 with an as-tested price of $67,130, while the BMW is a few grand more. The 550i starts at $60,575 and our tester topped $70K with options.
What's the Motivation Here?
The BMW 550i's interior is a well-thought-out, no-nonsense affair designed around the driver. The Infiniti M56's interior is a far more interesting design than the BMW's. Although the control layout appears complex, most operations are fairly easy to comprehend quickly.
Turbocharged engines are quickly becoming the norm at BMW, and now the 550i is on board. Its direct-injected 4.4-liter twin-turbo V8 produces 400 horsepower at 5,500 rpm and 450 pound-feet of torque from 1,750-4,500 rpm. Yes, that's a massive torque curve, but it comes at the expense of the old V8's rumbling exhaust. Now there's little more than a muted growl, and you can't even hear the turbos working their magic.
The 2011 Infiniti M56 uses cubic inches and plenty of revs to achieve its power. Its 5.6-liter V8 is good for 420 hp at 6,000 rpm and 417 lb-ft of torque at 4,400. It's no dinosaur, also utilizing direct-injection and variable valve timing and valve lift for a smooth, reasonably efficient power plant.
A little more driver involvement is required to get the most out of the M56's V8, though, as its power is concentrated at higher engine speeds. The Infiniti sounds more like a sport sedan than the BMW, especially when it approaches the 6,700-rpm redline.
By the Numbers
The Infiniti M56 forgoes turbos in favor of big displacement, its 5.6-liter V8 pumping out 420 hp and 417 lb-ft of torque. It also likes (and needs) to be revved higher than the BMW. Without question, this is one of the very best parts of the 2011 BMW 550i: a 4.4-liter twin-turbo V8 with 400 hp and 450 lb-ft of torque. It's the definition of a silky-smooth operator.
At our test track, the M56 was slightly quicker to 60 mph than the 550i, 5.0 to 5.2 seconds, respectively (4.7 and 4.9 seconds with a 1-foot rollout, as on a drag strip). So the BMW is slower, despite the fact that it's capable of getting a near-perfect amount of wheelspin off the line thanks to power-braking, something the Infiniti's brake-override system won't allow.
So how come the BMW is slower? Might have something to do with the extra 287 pounds of ballast the 4,380-pound 550i carries versus the M56. Seriously, what's a 5 Series doing weighing nearly 4,400 pounds? This is "EfficientDynamics?"
Weight aside, by the time the 550i hits the quarter-mile, its twin-turbo V8 inches the BMW ahead by 0.1 second (13.2 vs. 13.3); it's also traveling a lot faster at this point — 108.3 mph against the Infiniti's 106.7.
A Shifty Pair
The BMW front seats are wide and plush, although the leather isn't as soft and rich as what's found in the Infiniti. The M56's sport seats are stiffer than the BMW's, but still plenty comfortable. Some editors found the driving position a bit too high, as if you were sitting more on the car than in it, as with the BMW.
The BMW 550i comes standard with a six-speed manual transmission, but our test car was fitted with the no-cost-option eight-speed automatic. BMW says this new tranny's two additional ratios (over the old six-speed auto) come with no increase in size or weight.
It's a smooth operator in full automatic mode and easy to shift when you want to take control of the gears yourself. Not only does it shift in our preferred pattern (forward for downshifts, back for upshifts), it also blips the throttle when you grab a lower gear to match revs. It's not actually a true full manual mode, though, as a stomp on the gas will call up a multigear downshift. It doesn't hold gears either. If you hit the redline, you get the next cog whether you like it or not.
Infiniti offers just one transmission in the M56, a seven-speed automatic with four driver-controlled modes that affect transmission and throttle mappings. As with the BMW, leaving the center console shifter in "D" gives supremely smooth automatic shifting. But moving the center console lever toward the driver puts it in Manual mode, bringing the optional leather-covered, steering-column-mounted magnesium paddle shifters into play. The control is fully with the driver at this point, as the transmission will neither shift up nor down without consent from the paddle shifters. Downshift under braking and it rev matches, too.
These Are Sport Sedans, After All
This is what the Infiniti M56 is exceptionally good at — attacking turns with sports-car vigor. The BMW 550i won us over with its smooth and powerful twin-turbo V8 and excellent automatic transmission. It still handles corners well, but would be even more capable if its electric steering offered more feel.
With all of the BMW's high-techery, you'd think it would easily handle the Infiniti when the going gets twisty. Not so, especially in terms of instrumented testing. The M56 bested the 550i by 1.2 mph through the slalom (66.7 vs. 65.5 mph, respectively) while generating 0.89g around the skid pad against the BMW's so-so 0.84g.
The blame for the 550i's less-than-stellar performance doesn't lie purely with its all-season tires either, as they provided enough grip for it to stop almost as well as the M56 — just 1 foot longer from both 30 and 60 mph. The BMW's pedal felt stronger at the test track, but when pushing hard on back roads the Infiniti's optional ($370) high-friction brake pads felt more consistent.
More than anything, the 550i is simply too heavy and softly sprung for aggressive back-road driving. Even with the suspension at its stiffest setting, the 550i exhibited a surprising amount of understeer, while the 5's electric power steering feels artificial. You can still flog the 550i, but you won't feel completely in touch with the car.
The Infiniti isn't spot-on either. Its variable-assist steering, combined with the optional four-wheel active steering (the rear wheels are turned in phase with the front wheels, depending on vehicle speed and steering angle), makes for overly quick turn-in at low to medium speeds, alarmingly so at times.
But it's clear the driver seat of the Infiniti is the place to be when you pick up the pace on any kind of curvy road. The M56's steering becomes more and more natural as speeds increase, while the stiff suspension soaks up turns, if not bumps, with ease. The whole M56 experience, from its quick steering to its stiff suspension, is a bit on the frenetic side, but it's more engaging than the vague BMW.
There is one area where the BMW trumps the Infiniti on the fun scale — powerslides. Now, the average enthusiast may not find this very relevant, but in the right hands the BMW's electronic limited-slip rear differential does allows you to utilize the twin-turbo V8's prodigious low-end torque to induce some wicked corner exits. And that's all we'll say about that.
When You're Not Laying Rubber
If we drove only on twisty roads, the Infiniti would be our choice. But we don't. The stiff, nonadjustable suspension of the Sport Package is probably a little too serious for most luxury sedan buyers.
Our enthusiasm for the Infiniti drops slightly the moment the road gets bumpy, or basically any time you're just driving from A to B. The M56's stiff, nonadjustable suspension makes the average commute tiresome and unnecessarily jumpy. The tire and road noise is also a bit much for a luxury sedan, too. Basically, this car reminds you that you bought the Sport package every time you drive it.
The BMW, on the other hand, is always plush and serene. The same sedan that can execute tire-smoking powerslides can also tame mangled city streets. We would still prefer more steering feedback, but the trade-off is slightly less sawing at the wheel during normal driving. It's still a sport sedan, but one you can live with.
No Cabin Fever Here
You sit lower in the BMW's rear seat than in the Infiniti, and as such there's more headroom to be found. You won't feel like a second-rate passenger if you're riding in the backseat of the Infiniti. It's ultra-comfortable and the seatbacks have a nice rearward rake to them.
When you pay around $70,000 for a luxury sport sedan, you expect to be coddled, and neither car disappoints. Both are extremely comfortable places to spend time, the BMW's front seats getting the nod for their width and comfort, the Infiniti's for lateral support.
The M56's rear seat is more plush, while the BMW has more headroom. Fine leather and wood abound, as do such niceties as power rear window shades and excellent navigation systems, the BMW in particular boasting an impressive 10.2-inch transreflective screen that becomes easier to see in direct sunlight — the exact opposite of many systems.
In general the BMW's controls have better detents and are more ergonomic, while the Infiniti's are easier to decipher from the moment you sit in the car. And yes, iDrive Version 4 can still be a bit nonintuitive.
When it comes to interior design, though, the Infiniti has a more interesting take on luxury. The mix of materials in the M56 is more modern and stylish without looking overdone. The 550i has plenty of high-quality stuff; it's just on the sterile side.
And the Winner Is...
Surprisingly, the 550i didn't win the performance category of our ratings, but proved stronger than the M56 in the other categories.
As athletic and well-mannered as the Infiniti is on back roads, the BMW 550i squeezed out a win by 2.2 points. Why?
The BMW 550i is simply a better all-around sedan. Infiniti may have figured out the sport sedan piece of the formula, but BMW is better at making a sport sedan that you can live with. We like a tightly wound sedan as much as the next enthusiast, but we don't want to be reminded of the car's capabilities every time we head to the office. It's a fine line for sure, but one the Infiniti still needs to work on.
With the 550i, you get the refined driving experience along with plenty of sport sedan capability. Should it weigh less? Yes. Would we prefer more precise steering? Yes again. The new 5 Series is by no means perfect, but it still puts all the pieces together in a way that makes it feel like a proper luxury sport sedan. The Infiniti is close, but the BMW is already there.
1st Place: 2011 BMW 550i - From its lag-free twin-turbo V8 to its slick eight-speed automatic and adaptive suspension, the new 550i is a smooth operator. It's also gained about 400 pounds, and as such has lost a share of its handling edge.
2nd Place: 2011 Infiniti M56 - Infiniti paints the M56 as a serious sport sedan, and it definitely has the handling numbers to back up its intentions. The M56's modern interior is fancy, but the stiff suspension grows tiresome.
Track Test Results
0-30 mph (sec.) 2.1
0-45 mph (sec.) 3.5
0-60 mph (sec.) 5.2
0-75 mph (sec.) 7.1
1/4-mile (sec. @ mph) 13.2 @ 108.3
30-0 mph (ft.) 28
60-0 mph (ft.) 114
Slalom, 6 x 100 ft. (mph) 65.5
Skid pad, 200-ft. diameter (lateral g) 0.84
Curb weight, as tested (lbs.) 4,380
Weight distribution, as tested, f/r (%) 52/48
Edmunds observed (mpg) 18.6
As-tested MSRP $70,450
Acceleration Comments - Considering that the BMW 550i weighs almost 4,400 pounds, it gets off the line well. But it really came alive when power braking with stability and traction control turned off, allowing for a near-perfect amount of wheelspin. The third run overall (first with power braking) was quickest, but the final (sixth) run was barely any slower, showing good aversion to heat soak.
Braking Comments - Although braking distances varied by several feet with each run, randomly longer and shorter over the first five stops, the BMW's pedal travel barely changed and its feel remained very solid, while control under panic braking was always stable.
Handling Comments - Skid pad: The BMW's all-season run-flat tires did the best they could around the skid pad, hampered by the car's soft suspension and hefty curb weight. Attitude is steady-state understeer. It was possible to circle at nearly full throttle with the stability system turned on, the computer cutting power to keep the car from straying off line. Slalom: Not easy due to slow-reacting, lackluster-feeling electric steering, but the chassis offers decent feedback. The stability system wasn't overly intrusive when it came on, but you can go faster without it.
0-30 mph (sec.) 2.2
0-45 mph (sec.) 3.4
0-60 mph (sec.) 5.0
0-75 mph (sec.) 7.2
1/4-mile (sec. @ mph) 13.3 @ 106.7
30-0 mph (ft.) 29
60-0 mph (ft.) 113
Slalom, 6 x 100 ft. (mph) 66.7
Skid pad, 200-ft. diameter (lateral g) 0.89
Curb weight, as tested (lbs.) 4,093
Weight distribution, as tested, f/r (%) 55/45
Edmunds observed (mpg) 18.0
As-tested MSRP $67,130
Acceleration Comments - Turning the stability control system off made no difference in the way the M56 launched. But power braking did affect numbers, despite the fact that the system would only allow about 1,600 rpm. Regardless, we never got any wheelspin at the drag strip. Although the M56 would start a bit sluggishly off the line, its naturally aspirated V8 revved very hard once under way.
Braking Comments - Very good brake performance in terms of stopping distances, lack of fade and pedal feel. The pedal actually got less spongy the more stops we did; the optional R Spec high-friction brake pads probably help here.
Handling Comments - Skid pad: The Infiniti is very sensitive to throttle input. Its line around the skid pad is therefore very correctable, but if you get too aggressive with drop-throttle to tighten the line, it will oversteer and ruin the run. Slalom: The Infiniti's steering is quick, a bit more so than you'd expect in a car of this size. But it hustles around the slalom cones pretty quickly with ESC off. ESC on allows a fair amount of oversteer before it starts adding brakes to the wheels -- but it's abrupt and speed-sapping when it does.
A twisty road in Malibu beckons the 2011 BMW 550i and the 2011 Infiniti M56.
By Mike Mo*****llo, Road Test Editor | Published Dec 28, 2010
When it comes to respectability in the midsize sport sedan segment, all roads lead through BMW's 5 Series. It's been ruling this class for decades now, and for good reason. It has the uncanny ability to satisfy both driving enthusiasts and buyers who are simply looking for a luxury sedan with German cachet.
Now that the all-new twin-turbo 2011 BMW 550i is here, it was time to see just how well it stacks up against its newest competitors. But instead of going toe-to-toe with a classic European rival, we figured a match-up with the latest from Japan would be more interesting. For that we turned to the all-new 2011 Infiniti M56, a thoroughly redesigned sedan that is once again aiming for the Germans. It has all the makings of a worthy competitor, but how does it hold up on the road?
How They Stack Up
You wouldn't be the first person to mistake the new 5 Series for the 7 Series, or vice versa, their styling is so similar. The M56 was designed as a serious sport sedan, made even more so by the optional Sport package our test car was outfitted with.
Not surprisingly, the 2011 BMW 550i and 2011 Infiniti M56 have plenty of similarities. Both are rear-drive sedans powered by sizable V8s. In this case, both are hooked to automatic transmissions, a seven-speed in the Infiniti and an eight-speed in the BMW.
To make sure no one whines about "stacking the deck" in one car's favor, both the 550i and the M56 were outfitted with Sport packages. The Infiniti's $3,650 option adds a stiffer suspension with upgraded springs and shocks, larger brakes, Bridgestone Potenza RE050A summer performance tires on 20-inch alloy wheels, four-wheel active steer, paddle shifters, sport seats and a unique steering wheel and shift knob.
The BMW 550i had the benefit of both a Dynamic Handling package, which includes electronic damping control, active roll stabilization (active antiroll bars) and Adaptive Drive (allowing for specific chassis/drivetrain settings) for $2,700, as well as a $2,200 Sport package, which adds a sportier leather steering wheel, multicontour seats, special exterior trim, an increased top speed (limited to 150 mph) and — surprisingly — 19-inch Goodyear Excellence run-flat all-season tires.
Technology and luxury abound in these cars, the kind of niceties that make your drive safer (the BMW's standard adaptive cornering headlights) and more relaxing (Infiniti's standard heated and cooled front seats). Differences come in the form of which features each manufacturer supplies standard, and which ones they make you pay extra for — as an example, you can get those adaptive headlights on the Infiniti, but it'll cost $3,000 as part of the Technology package; conversely, neither heated nor cooled front seats come standard in the BMW — heated seats cost $500 (or could be part of a package), while seat cooling tacks on another $1,950-$2,950 depending on the package.
As you might have guessed, these are expensive sedans. The M56 starts at $58,765 with an as-tested price of $67,130, while the BMW is a few grand more. The 550i starts at $60,575 and our tester topped $70K with options.
What's the Motivation Here?
The BMW 550i's interior is a well-thought-out, no-nonsense affair designed around the driver. The Infiniti M56's interior is a far more interesting design than the BMW's. Although the control layout appears complex, most operations are fairly easy to comprehend quickly.
Turbocharged engines are quickly becoming the norm at BMW, and now the 550i is on board. Its direct-injected 4.4-liter twin-turbo V8 produces 400 horsepower at 5,500 rpm and 450 pound-feet of torque from 1,750-4,500 rpm. Yes, that's a massive torque curve, but it comes at the expense of the old V8's rumbling exhaust. Now there's little more than a muted growl, and you can't even hear the turbos working their magic.
The 2011 Infiniti M56 uses cubic inches and plenty of revs to achieve its power. Its 5.6-liter V8 is good for 420 hp at 6,000 rpm and 417 lb-ft of torque at 4,400. It's no dinosaur, also utilizing direct-injection and variable valve timing and valve lift for a smooth, reasonably efficient power plant.
A little more driver involvement is required to get the most out of the M56's V8, though, as its power is concentrated at higher engine speeds. The Infiniti sounds more like a sport sedan than the BMW, especially when it approaches the 6,700-rpm redline.
By the Numbers
The Infiniti M56 forgoes turbos in favor of big displacement, its 5.6-liter V8 pumping out 420 hp and 417 lb-ft of torque. It also likes (and needs) to be revved higher than the BMW. Without question, this is one of the very best parts of the 2011 BMW 550i: a 4.4-liter twin-turbo V8 with 400 hp and 450 lb-ft of torque. It's the definition of a silky-smooth operator.
At our test track, the M56 was slightly quicker to 60 mph than the 550i, 5.0 to 5.2 seconds, respectively (4.7 and 4.9 seconds with a 1-foot rollout, as on a drag strip). So the BMW is slower, despite the fact that it's capable of getting a near-perfect amount of wheelspin off the line thanks to power-braking, something the Infiniti's brake-override system won't allow.
So how come the BMW is slower? Might have something to do with the extra 287 pounds of ballast the 4,380-pound 550i carries versus the M56. Seriously, what's a 5 Series doing weighing nearly 4,400 pounds? This is "EfficientDynamics?"
Weight aside, by the time the 550i hits the quarter-mile, its twin-turbo V8 inches the BMW ahead by 0.1 second (13.2 vs. 13.3); it's also traveling a lot faster at this point — 108.3 mph against the Infiniti's 106.7.
A Shifty Pair
The BMW front seats are wide and plush, although the leather isn't as soft and rich as what's found in the Infiniti. The M56's sport seats are stiffer than the BMW's, but still plenty comfortable. Some editors found the driving position a bit too high, as if you were sitting more on the car than in it, as with the BMW.
The BMW 550i comes standard with a six-speed manual transmission, but our test car was fitted with the no-cost-option eight-speed automatic. BMW says this new tranny's two additional ratios (over the old six-speed auto) come with no increase in size or weight.
It's a smooth operator in full automatic mode and easy to shift when you want to take control of the gears yourself. Not only does it shift in our preferred pattern (forward for downshifts, back for upshifts), it also blips the throttle when you grab a lower gear to match revs. It's not actually a true full manual mode, though, as a stomp on the gas will call up a multigear downshift. It doesn't hold gears either. If you hit the redline, you get the next cog whether you like it or not.
Infiniti offers just one transmission in the M56, a seven-speed automatic with four driver-controlled modes that affect transmission and throttle mappings. As with the BMW, leaving the center console shifter in "D" gives supremely smooth automatic shifting. But moving the center console lever toward the driver puts it in Manual mode, bringing the optional leather-covered, steering-column-mounted magnesium paddle shifters into play. The control is fully with the driver at this point, as the transmission will neither shift up nor down without consent from the paddle shifters. Downshift under braking and it rev matches, too.
These Are Sport Sedans, After All
This is what the Infiniti M56 is exceptionally good at — attacking turns with sports-car vigor. The BMW 550i won us over with its smooth and powerful twin-turbo V8 and excellent automatic transmission. It still handles corners well, but would be even more capable if its electric steering offered more feel.
With all of the BMW's high-techery, you'd think it would easily handle the Infiniti when the going gets twisty. Not so, especially in terms of instrumented testing. The M56 bested the 550i by 1.2 mph through the slalom (66.7 vs. 65.5 mph, respectively) while generating 0.89g around the skid pad against the BMW's so-so 0.84g.
The blame for the 550i's less-than-stellar performance doesn't lie purely with its all-season tires either, as they provided enough grip for it to stop almost as well as the M56 — just 1 foot longer from both 30 and 60 mph. The BMW's pedal felt stronger at the test track, but when pushing hard on back roads the Infiniti's optional ($370) high-friction brake pads felt more consistent.
More than anything, the 550i is simply too heavy and softly sprung for aggressive back-road driving. Even with the suspension at its stiffest setting, the 550i exhibited a surprising amount of understeer, while the 5's electric power steering feels artificial. You can still flog the 550i, but you won't feel completely in touch with the car.
The Infiniti isn't spot-on either. Its variable-assist steering, combined with the optional four-wheel active steering (the rear wheels are turned in phase with the front wheels, depending on vehicle speed and steering angle), makes for overly quick turn-in at low to medium speeds, alarmingly so at times.
But it's clear the driver seat of the Infiniti is the place to be when you pick up the pace on any kind of curvy road. The M56's steering becomes more and more natural as speeds increase, while the stiff suspension soaks up turns, if not bumps, with ease. The whole M56 experience, from its quick steering to its stiff suspension, is a bit on the frenetic side, but it's more engaging than the vague BMW.
There is one area where the BMW trumps the Infiniti on the fun scale — powerslides. Now, the average enthusiast may not find this very relevant, but in the right hands the BMW's electronic limited-slip rear differential does allows you to utilize the twin-turbo V8's prodigious low-end torque to induce some wicked corner exits. And that's all we'll say about that.
When You're Not Laying Rubber
If we drove only on twisty roads, the Infiniti would be our choice. But we don't. The stiff, nonadjustable suspension of the Sport Package is probably a little too serious for most luxury sedan buyers.
Our enthusiasm for the Infiniti drops slightly the moment the road gets bumpy, or basically any time you're just driving from A to B. The M56's stiff, nonadjustable suspension makes the average commute tiresome and unnecessarily jumpy. The tire and road noise is also a bit much for a luxury sedan, too. Basically, this car reminds you that you bought the Sport package every time you drive it.
The BMW, on the other hand, is always plush and serene. The same sedan that can execute tire-smoking powerslides can also tame mangled city streets. We would still prefer more steering feedback, but the trade-off is slightly less sawing at the wheel during normal driving. It's still a sport sedan, but one you can live with.
No Cabin Fever Here
You sit lower in the BMW's rear seat than in the Infiniti, and as such there's more headroom to be found. You won't feel like a second-rate passenger if you're riding in the backseat of the Infiniti. It's ultra-comfortable and the seatbacks have a nice rearward rake to them.
When you pay around $70,000 for a luxury sport sedan, you expect to be coddled, and neither car disappoints. Both are extremely comfortable places to spend time, the BMW's front seats getting the nod for their width and comfort, the Infiniti's for lateral support.
The M56's rear seat is more plush, while the BMW has more headroom. Fine leather and wood abound, as do such niceties as power rear window shades and excellent navigation systems, the BMW in particular boasting an impressive 10.2-inch transreflective screen that becomes easier to see in direct sunlight — the exact opposite of many systems.
In general the BMW's controls have better detents and are more ergonomic, while the Infiniti's are easier to decipher from the moment you sit in the car. And yes, iDrive Version 4 can still be a bit nonintuitive.
When it comes to interior design, though, the Infiniti has a more interesting take on luxury. The mix of materials in the M56 is more modern and stylish without looking overdone. The 550i has plenty of high-quality stuff; it's just on the sterile side.
And the Winner Is...
Surprisingly, the 550i didn't win the performance category of our ratings, but proved stronger than the M56 in the other categories.
As athletic and well-mannered as the Infiniti is on back roads, the BMW 550i squeezed out a win by 2.2 points. Why?
The BMW 550i is simply a better all-around sedan. Infiniti may have figured out the sport sedan piece of the formula, but BMW is better at making a sport sedan that you can live with. We like a tightly wound sedan as much as the next enthusiast, but we don't want to be reminded of the car's capabilities every time we head to the office. It's a fine line for sure, but one the Infiniti still needs to work on.
With the 550i, you get the refined driving experience along with plenty of sport sedan capability. Should it weigh less? Yes. Would we prefer more precise steering? Yes again. The new 5 Series is by no means perfect, but it still puts all the pieces together in a way that makes it feel like a proper luxury sport sedan. The Infiniti is close, but the BMW is already there.
1st Place: 2011 BMW 550i - From its lag-free twin-turbo V8 to its slick eight-speed automatic and adaptive suspension, the new 550i is a smooth operator. It's also gained about 400 pounds, and as such has lost a share of its handling edge.
2nd Place: 2011 Infiniti M56 - Infiniti paints the M56 as a serious sport sedan, and it definitely has the handling numbers to back up its intentions. The M56's modern interior is fancy, but the stiff suspension grows tiresome.
Track Test Results
0-30 mph (sec.) 2.1
0-45 mph (sec.) 3.5
0-60 mph (sec.) 5.2
0-75 mph (sec.) 7.1
1/4-mile (sec. @ mph) 13.2 @ 108.3
30-0 mph (ft.) 28
60-0 mph (ft.) 114
Slalom, 6 x 100 ft. (mph) 65.5
Skid pad, 200-ft. diameter (lateral g) 0.84
Curb weight, as tested (lbs.) 4,380
Weight distribution, as tested, f/r (%) 52/48
Edmunds observed (mpg) 18.6
As-tested MSRP $70,450
Acceleration Comments - Considering that the BMW 550i weighs almost 4,400 pounds, it gets off the line well. But it really came alive when power braking with stability and traction control turned off, allowing for a near-perfect amount of wheelspin. The third run overall (first with power braking) was quickest, but the final (sixth) run was barely any slower, showing good aversion to heat soak.
Braking Comments - Although braking distances varied by several feet with each run, randomly longer and shorter over the first five stops, the BMW's pedal travel barely changed and its feel remained very solid, while control under panic braking was always stable.
Handling Comments - Skid pad: The BMW's all-season run-flat tires did the best they could around the skid pad, hampered by the car's soft suspension and hefty curb weight. Attitude is steady-state understeer. It was possible to circle at nearly full throttle with the stability system turned on, the computer cutting power to keep the car from straying off line. Slalom: Not easy due to slow-reacting, lackluster-feeling electric steering, but the chassis offers decent feedback. The stability system wasn't overly intrusive when it came on, but you can go faster without it.
0-30 mph (sec.) 2.2
0-45 mph (sec.) 3.4
0-60 mph (sec.) 5.0
0-75 mph (sec.) 7.2
1/4-mile (sec. @ mph) 13.3 @ 106.7
30-0 mph (ft.) 29
60-0 mph (ft.) 113
Slalom, 6 x 100 ft. (mph) 66.7
Skid pad, 200-ft. diameter (lateral g) 0.89
Curb weight, as tested (lbs.) 4,093
Weight distribution, as tested, f/r (%) 55/45
Edmunds observed (mpg) 18.0
As-tested MSRP $67,130
Acceleration Comments - Turning the stability control system off made no difference in the way the M56 launched. But power braking did affect numbers, despite the fact that the system would only allow about 1,600 rpm. Regardless, we never got any wheelspin at the drag strip. Although the M56 would start a bit sluggishly off the line, its naturally aspirated V8 revved very hard once under way.
Braking Comments - Very good brake performance in terms of stopping distances, lack of fade and pedal feel. The pedal actually got less spongy the more stops we did; the optional R Spec high-friction brake pads probably help here.
Handling Comments - Skid pad: The Infiniti is very sensitive to throttle input. Its line around the skid pad is therefore very correctable, but if you get too aggressive with drop-throttle to tighten the line, it will oversteer and ruin the run. Slalom: The Infiniti's steering is quick, a bit more so than you'd expect in a car of this size. But it hustles around the slalom cones pretty quickly with ESC off. ESC on allows a fair amount of oversteer before it starts adding brakes to the wheels -- but it's abrupt and speed-sapping when it does.
