Story by Benjamin Greene
Originally published by Dupont Registry: http://www.dupontregistry.com/autos/NewsCenter/NewsCenterDetails.aspx?mmysid=4049
The S400 Hybrid offers S-Class levels of luxury and space and returns 19 miles to the gallon in the city and 25 on the highway, an improvement of 20 percent and eight percent, respectively, compared to the S550. But, at a mere $2,000 less but a whopping 100-hp shy compared to the V-8 offering, the S400 doesn’t win a decisive victory over its stablemate. Sure, it uses less fuel and emits less CO2, but a car of this class shouldn’t offer concessions. But that is just what you get with the S400 Hybrid, concessions.The S400 Hybrid also offers the lowest level of carbon dioxide emissions worldwide for its vehicle segment. Mercedes-Benz has even gone as far as to call the S400 Hybrid the “CO2 champion of the luxury class.” For some, the case to buy the S400 Hybrid is made with that statement alone.
But we believe that the owners of an S-Class demand sufficient power, something the S400 Hybrid is lacking. It’s not like the BMW ActiveHybrid 7, which is able to create a massive 455 hp while returning 17-mpg city and 26-mpg highway and can scoot to 60 mph from a standstill in 4.7 seconds. Or even the Lexus LS600hL, which musters 438 hp, returns 19-mpg city and 23-mpg highway, and can hit 60 mph in 5.5 seconds. The S400 Hybrid achieves competitive gas mileage, but creates a miserable 295-combined hp and requires 7.2 seconds to get to 60 mph from a stop. The in-seat impressions confirm the disparity in power.
The S400 Hybrid’s powerplant is based off the S350, a car found in Europe. Under the hood of the S400 Hybrid is the S350’s 3.5-liter 275-hp V-6. Between the motor and the seven-speed automatic transmission is a 20-hp electric motor. A 120-volt lithium ion battery powers the electric motor and is revived through the braking system (this is the likely culprit behind the inconsistent brake pedal feel that one tester detested). The hybrid system works in either an Eco or a Sport mode to provide the desired power and fuel economy. The system can go as far as to cutoff the engine below nine mph, even when braking to a stop, to yield a better return. Unfortunately, at traffic lights, we did experience a slight delay from when we released the brakes to when the gasoline engine re-started.
The battery pack’s compact dimensions allow it to be stored in the engine compartment. This keeps it from intruding into the normal S400’s trunk or passenger space and allows it to offer the same room and convenience features as any other S-Class.
We give Mercedes-Benz accolades for building its first full-size luxury hybrid; however, the car’s lack of power, inconsistent brake feel, and the delay in engine starts at full stops makes the Mercedes-Benz S550 our first choice in terms power and price despite using more fuel.
295 hp @ 6,000 rpm (combined output)
284 lb-ft @ 2,400 rpm (combined output)
CO2 champion of the luxury class
Also test drive the S550