Mercedes-Benz’ hybrid version of its premier S-Class series, the S400HV is the relatively eco-friendly version of an otherwise world standard bearer sedan.

A little bit different from how other top German automakers do it, this one is a mild hybrid, actually makes less power not more than stable mates, and is lower priced, not mid-level or near the top of the series.

As an S-Class, it gives up nothing in ultra-luxurious refinement, and European tests have verified the car is at home on the Autobahn, if not as much as over-powered V8 and V12 versions.

We said this was entry level, but in S-Class territory, this still means $92,350 and up, and so one would expect all the accolades even if others in its line can more than double this price point.


Motive power for the car is a 3.5-liter V6 paired with an electric motor sandwiched between the engine and the specially adapted seven-speed automatic transmission.

Total system power is a respectable 295 horsepower and 284 pound-feet of torque. Of this, the electric motor contributes 20 horsepower and 118 pound-feet. The premium gas-burning engine offers 275 horsepower.

The S400HV was the first hybrid to offer a compact lithium-ion battery. It’s a 32-cell, 120-volt, 0.9 amp-hour charged by the motor generator and regenerative braking.

Since this is a mild hybrid, the car is not able to run on electric power alone, but the hybrid system, aided also by a stop-start system, and intelligent engine management system does yield a gain in economy.


Its 21 mpg combined is superior to the 4.7-liter V8-equipped S550, but less than the clean diesel variety priced very close.

Mercedes-Benz first introduced this car in 2010 when the S-Class was refreshed, and the model carries forth again for 2013 with no changes.

Speaking with Mercedes-Benz, we were told to expect a new S-Class V8, but the company has not yet said whether a 2014 S hybrid will also be introduced.

For a more thorough review of the S-Class Hybrid, please also consult our 2012 review of the same car, or Mercedes-Benz’ Web site.