2011 Infiniti M37 and M56 Test Drive

San Diego, Calif.—Two months ago we had a chance to spend some time behind the wheel of prototype versions of Infiniti's new M37 and M56 sedans. We were certainly impressed. But it's difficult to judge a luxury car when there are still some rough edges to smooth out.

Well, after driving the production sedans for a day on some challenging driving loops in the mountains near San Diego, we can say these new Infinitis are assuredly smooth. The midsize luxury sedan class has been heating up thanks to recent launches of the new Mercedes-Benz E-Class and BMW 5 Series. Are these Infinitis capable and comfortable enough to take on these legendary German rivals? Let's find out.

The Specs

Under the hood of the $46,250 M37 is the familiar 3.7-liter VQ-series V6, now rated at 330 hp and 270 lb-ft of torque. But the biggest news, for those who relish the thrust from V8 power, is the motor in the $57,550 M56. The new 5.6-liter V8 is rated at 420 hp and 417 lb-ft of torque. Both engines are paired to a seven-speed automatic and all-wheel drive is optional.

M37s are rated to deliver 18 mpg city and 26 highway, while the V8 M56 model's performance dips slightly to 16 mpg city and 25 highway.

Like nearly every other car in Infiniti's lineup—with the exception of the hulking QX56 SUV—the new M sedans ride on an updated version of the company's FM platform. This architecture is so flexible it can underpin cars as varied in size and mission as the Nissan 370Z and the Infiniti FX crossovers.



Unlike most new car redesigns today, the dimensions of the M have not grown by much in this latest generation—it is wider by 1.5 inches, lower by a fraction of an inch and slightly longer too. But the wheelbase remains the same, and that means the interior provides roughly the same roominess as the old car. The new Ms haven't gained much weight either, the M37 at 3858 pounds is 6 pounds less than the old car and the M56 is 70 pounds more than the old M45.

The focus of the new M's chassis was refinement. Upfront, the double-wishbone suspension remains largely the same. But in the rear, the multilink design has been heavily modified with far beefier-looking lower links, retuned rubber bushings and a new coilover shock design. The goal? Increase comfort without loosing any of the sportiness.

Speaking of the "s" word, a sport package can be optioned on either the V6 or V8 cars. This includes larger 14-inch front rotors (13.8-inch in the rear) along with new dual-piston shocks, four-wheel steering (up to 1-degree rear steer in phase with front wheels) and 20-inch wheels with summer tires—amongst numerous interior upgrades such as magnesium paddle shifters and thicker bolstered seats.

The new M is packed with technical prowess too. There's a standard Drive Mode Selector that will vary throttle progression and transmission shift mapping for one of four modes, standard, sport, eco and snow.

The option list is deep with new tech too. There's not only a blind-spot warning system but also Blind Spot Intervention that uses cameras and individual wheel braking to guide the car away from a lane that is occupied. Similarly, Active Trace Control will use selective individual wheel braking to set the car up for an upcoming corner—it's almost like a pre-stability control. The system doesn't make the new M corner any more quickly, but it does smooth out transitions.

Read more: 2011 Infiniti M37 and M56 Test Drive - Popular Mechanics