2012 Mercedes-Benz CLS550

2012 Mercedes-Benz CLS550

The new CLS is incrementally larger in every dimension than the outgoing CLS — about an inch longer, a half-inch higher and less than a half-inch wider. Wheelbase grows by 0.8 inch to 113.2 inches. There's fractionally more shoulder room inside, though the dramatically curved roof line still compromises rear headroom, kind of like a, um, coupe.

Despite the larger frontal area, drag has been reduced by 10 percent thanks to an improvement in the drag coefficient to a slippery 0.26. Static bending and torsional stiffness are up 28 and 6 percent, respectively. The beefier body shell adds weight — so although the new CLS boasts new all-aluminum doors, hood, deck lid and parcel shelf, it checks in about 140 pounds heavier than the old CLS.

U.S.-bound CLSs will offer one powertrain at launch as opposed to the cornucopia of offerings overseas. A new — largely new, anyway — 4.6-liter V8 boasts twin Honeywell GT2260 turbochargers and direct injection that join forces to create 402 horsepower, an increase of 20 compared to the outgoing normally aspirated 5.5-liter mill upon which it's based. The familiar seven-speed autobox is, predictably, the only transmission available.

Torque is what's for dinner in cars like the CLS, and that's a particular specialty of the force-fed bent-eight, as there are 443 pound-feet on tap from 1,600-4,750 rpm.

New active all-LED headlights are said to be a world's first, too. Designed to last the life of the car, they automatically dip the cutoff and modulate the high beams in response to oncoming traffic and driving conditions. Very clever indeed. In action each headlight's central nodule eerily pivots around like some kind of sentient being.

Some of the efficiency improvement is due to a stop/start engine function that won't initially be available in stateside CLSs, as compliance of the system with U.S. emissions isn't finalized. Still, this engine is a win-win situation on all fronts. It even sounds terrific as it maintains an exhaust note that suggests ample meat lurks underhood.