The 2011 Infiniti M37 and M56 replace the 2010 M35 and M45. The difference in name reflects switches to a 3.7-liter V-6 and a 5.6-liter V-8, both of which provide more power, as you'd expect. Many other upgrades come with this complete redesign.
Though beautifully styled inside and outside, the redesigned 2011 Infiniti M sport sedan is frustrated by some quirks and glitches, and it's not as affordable as it used to be.
The M comes in three versions: the M37, M56 and an all-new hybrid version, the M35h. The gas-only versions are rear-wheel drive but offer optional all-wheel drive (designated by the "x" suffix). Unlike some competitors, including the BMW 5 Series and Acura TL, the M sedan doesn't offer a manual transmission. We tested the M37x and both the M56 and M56x, but did not drive the M35h.
Though the car impresses, its sport-sedan billing leads me to start with my main complaint: The seven-speed automatic transmission has a chronic case of indecision. Stomp on the accelerator from a standstill, and all is well. Ditto for normal, sedate driving. But when the time comes to pass or get moving more quickly once you're already in motion, the car bogs down as the transmission hunts for a gear.