Mercedes S550 Plug-in Hybrid Review

Mercedes S550 Plug-in Hybrid Review

It's hard to find flaws in a Mercedes S-Class. In the past, power and comfort came at some price in terms of fuel efficiency. With the S550 Plug-in Hybrid, you get all the benefits of the Mercedes flagship sedan, but now with 20 miles of all-electric range and (depending on how you drive and charge) as much as 40 miles per gallon.

Performance:The powertrain is comprised of a gas-powered 329-horsepower V-6 engine and an 85-kilowatt electric motor (pulling juice from an 8.7 kilowatt-hour battery)—all integrated with a Mercedes seven-speed automatic transmission. Put that together for 436 horses worth of oomph. Zero-to-60 mph acceleration time is 5.2 seconds, according to Mercedes.

The battery’s pack energy storage, of which 6.4 kWh is usable, means up to 20 miles of all-electric driving, if traveling below 87 mph. After those electric miles, the capable V-6 is put to use, with a top speed governed at 130 mph. A haptic kick down-like mechanism on the accelerator pedal helps drivers maintain electric mode, and otherwise drive with maximum efficiency—or consciously decide to push into the pedal for more power.

Four different modes allow drivers to decide emphasize when to use or save the battery’s energy. Or you can simply allow the computer to make the decision. Those decisions are probably smarter than your own—especially when using the S-50’s navigation system. That’s because the navigation, along with radar guidance, will use data about hills, valleys and other topography to calculate the best mode for optimized performance, energy regenerative and overall efficiency.

Reviewers who drove a pre-production model are divided handling—due to extra weight from the battery pack. Some say the S550 plug-in hybrid handles exactly like the gas version, while others believe the extra 650 pounds makes the car less adept at cornering. While that point is debatable, there’s no doubt that the V-6, even with the electric boost, is not as speedy and smooth as the non-plug S550’s 4.7-liter V8. The same concerns were expressed about the regenerative braking, which to some felt different than traditional brakes. Others, such as Road and Track, say that Mercedes is among the first automakers to “get regenerative brakes done right” and that it’s “natural and almost entirely seamless.”

Charging:There’s nothing unusual about the S550’s charging process. If the pack is completely depleted, you can fully replenish it in about two hours from a 240-volt charging station. Or if you choose to use a standard 120-volt outlet, expect a charging time closer to four or five hours. That’s easily accomplished by plugging in every night. Still, it’s nice to be able to come home for a quick pit stop to maintain more all-electric driving—so a home 240-volt charging station is recommended.

The investment in a good home charging setup will come in handy for future possible electric cars with bigger batteries. At some point, you might want an all-electric BMW, Mercedes or Tesla as a garage mate to your plug-in S-Class.

MERCEDES S550 PLUG-IN HYBRID SPECIFICATIONS

Availability:	Now
Base MSRP:	TBD
Est. tax credit:	$4700
Technology:	Plug-in Hybrid
Body type:	Sedan
Seats:	5
EPA Range:	20 miles electric + gasoline
Battery size:	8 kWh
Charging rate:	3.3 kW