New Mercedes-Benz S550 Plug-in Hybrid charges for extra efficiency

The first plug-in hybrid car from Mercedes-Benz weighs 5,093 lbs., hits 62 mph in 5.2 seconds and will likely carry a price tag thousands higher than the S-Class sedan on which it is based. The German carmaker calls the S550 Plug-In Hybrid — the full name as it appears on the trunk — the first model of a new plug-in hybrid fleet. But why did it start with its largest and most expensive sedan?

Because it has to start somewhere.

The S-Class now serves as the test bed for new Mercedes technologies; systems like the nearly autonomous driving and pedestrian avoidance unveiled in the S-Class have trickled down through the entire line. With its high sticker price, Mercedes-Benz can afford to finance and test new efforts first in the S550 that it plans to implement in other, smaller models.

And as one of the few automakers that pays fines to the U.S. government for falling short of ever-increasing fuel economy standards, Mercedes has to run to catch up with its powerful but thirsty fleet.

“There’s no clear roadmap of what will happen with emissions rules," said Thomas Weber, head of development for Mercedes passenger cars, "but it’s clear that Mercedes-Benz needs to start development today."

The Plug-in Hybrid pairs an electric motor and a twin-turbo V-6 for a total of 442 hp with 479 ft-lbs of torque combined, a slight step down from the regular S550 with 449 hp with 516 ft-lbs of torque. The S550 Plug-In Hybrid can go roughly 20 miles on a single charge and takes 2 to 3 hours to fully recharge, depending on voltage; Mercedes-Benz is working on wireless charging that could be installed under the floor of a garage, rather than requiring the socket in the back bumper.