Hybrid luxury vehicles are by no means new, but hybrid luxury sedans that actually boast real fuel-economy gains—not just power, weight, and price increases—are. This Mercedes-Benz S400 is the first full-boat luxo-hybrid with markedly better fuel economy (by about 20 percent, to a Camry V-6–like 19 mpg city and 26 mpg highway) and a lower price ($88,825 versus $92,475 for an S550) than its conventionally powered brethren, making it the S-class model that is cheapest to buy and to operate.
The S400 is a mild hybrid, meaning the additional electrical components are not configured in a way that allows them to drive the wheels by themselves. The 20-hp electric motor instead assists the 275-hp, 3.5-liter V-6 in accelerative duties and supports ancillary systems such as the climate control and power accessories. These hybrid components aren’t so heavy as to excessively weigh down the S-class. Oh, yeah, and who is going to complain about an extra bit of torque—118 lb-ft at 0 rpm from the electric motor—ready to boost low-end response? Certainly not us.
