Midsize luxury cars run the gamut from comfortable to rigid; the M is closer to rigid, though not so much that it's punishing to drive. My test car last year had the Sport package — which augments the four-wheel-independent suspension with sportier tuning, bigger wheels and high-performance summer tires — but ride quality was livable, and even more so in the M35x I drove this year, which had smaller wheels and regular suspension tuning. Highway road noise remains tolerable up to 75 mph — above that, wind and road noise quickly encroach — and the car's chassis dispatches bumps with modest noise and few reverberations.

If you live near curvy roads, you'd do well to drive them in the M. The steering wheel moves with a lighter touch than in Infiniti's smaller G37, and though it doesn't feel as precise in prolonged bends — highway cloverleafs, curvy backroads — the turn-in precision for lane changes and most city driving is in the same league. The steering feel encourages twisty-road driving in a way a Volvo S80 or Mercedes E-Class cannot. Body roll remains well in check, and at its limits the M displays good grip and even better balance. The Sport package adds Infiniti's Rear Active Steer, which power-adjusts the suspension hardware to angle the rear wheels slightly while the car is turning. The purported result is swifter handling. Last year's M35 came equipped with the feature, but I couldn't tell when the system was operating, or what benefits it added. The M never once came off as unresponsive, though, so evidently the extra hardware did its job.

Rear-wheel-drive models increase the M's turning circle to 36.7 feet, as opposed to 36.1 feet with all-wheel drive. Those figures are on the tighter side of the competition.