Mercedes' first-ever hybrid is about to drop, in the form of a luxury sedan. But if you look at the S-class roster, there's a big problem: the diesel.
Something occurred to me as I was reading through last week's test of the Mercedes-Benz S400 Hybrid in the German magazine Auto Motor und Sport: the S400 has a big problem. The S350 CDI.
Firstly, the S400 is similar in concept to Honda's Integrated Motor Assist hybrid system, which means it uses a small motor/generator sandwiched between the engine and transmission. The V-6 engine runs on the Atkinson cycle, which means it's more efficient but produces little low-end torque--but the electric motor's additional torque makes up for it. The Mercedes can't drive around on electric power alone, but the system gives both performance and fuel economy benefits compared to the regular S350, which uses a similar V-6.
Whereas the S350 needs 7.3 seconds to hit 100 km/h (62 mph), the S400 Hybrid does the sprint in 7.2. And the fuel economy benefits (at least on the EU cycle) are huge, with a drop in combined rating from 24 mpg to an impressive 30 mpg overall.
But here's the problem: the diesel-powered S350 CDI uses a V-6 engine that's a half-liter smaller (3.0 liters instead of 3.5), and its horsepower defecit means that needs an ever-so-slightly longer 7.8 seconds to hit 62 mph. But it returns 1.2 mpg better overall, for a total of 31 mpg. It even achieves the same electronically limited 155-mph top speed as the S400.
Here's the kicker: the S350 CDI is 12,316 euro cheaper -- a savings of $17,100 -- than the S350 CDI. And given that diesels tend to do better in real-world driving than they do in fuel economy testing, while hybrids are exactly the opposite, the S400 Hybrid will just continue to get more expensive over time. So why would you ever want the hybrid?
Well, because Mercedes doesn't bring the diesel to the US. Well, they do, but not in the S-class. If you were wondering why Mercedes (and the rest of those oh-so-logical German manufacturers) have been so slow to accept the idea of hybrids: they don't make financial sense when compared to diesels.
Mercedes should have just brought us the S350 diesel, slapped a big HYBRID logo on it, and called it a day. We'd all be better off.