The adage goes: "expensive diesel + expensive hybrid = expensive diesel hybrid."
A chief challenge to creating a viable parallel diesel hybrid system has been overcoming the sheer costs to the buyer. The adage goes: "expensive diesel + expensive hybrid = expensive diesel hybrid." This may be true on some levels, but we seem to have arrived at a point where the costs of scale are finally helping now that more and more joint ventures contribute to lower pricing.
The other issue has been refinement. Between the potentially rougher on-off nature of the high-compression diesel in a parallel hybrid luxury car alongside the desired start-stop function to help save even more fuel, refining drivetrain feel was simply a qualitative challenge. But from what I can tell based on my long drive of a pre-production E 300 BlueTEC Hybrid on both the European flatlands and over several mountainous passes, Mercedes seems to have the situation mostly licked.
As all manufacturers are realizing, they cannot just leave their stock V6 or V8 in the engine bay of their bigger cars, slap on a parallel hybrid system, charge a mess of money for it and call it good. When car buyers go hybrid, they are volunteering to change their performance expectations of their daily driver, and therefore must be more than willing to change their driving style to get the most out of the shift.
Accordingly, carmakers are currently looking through their vast array of sophisticated four-cylinders to help dramatically bring down the counterproductive weight of a big hybrid car or SUV. In the case of the well-executed E 300 BlueTEC Hybrid, Mercedes turns to its 201-horsepower 2.2-liter CDI, known internally as OM651, a powerplant currently seen in many European 220/230/250 CDI models. Versus the E 250 CDI BlueEFFICIENCY T-Modell (i.e. station wagon) in Europe at 4,070 pounds, the E 300 BlueTEC Hybrid T-Modell adds just over 200 lbs. With that weight you get the lithium-ion battery pack, electronic management system and a compact electric motor capable of 25 hp/184 pound-feet of torque integrated with the 7G-tronic transmission.
I managed to hit 44.4 miles per U.S. gallon and was impressed that the fuel needle barely moved.
You also get a potential range from the 15.6-gallon fuel tank of 870 miles. Over my 120-mile drive, I managed to hit 44.4 miles per U.S. gallon and was impressed that the fuel needle barely moved. One tester in our group managed 54.7 mpg but also admitted to "attracting the ire of many motorists" who were stuck following him. You know the frustrating style of driving I'm talking about. So, no, never in your wildest dreams could you hit 870 miles on a tank, but you could hit over 700 miles while driving fairly normally and pollute impressively little in the process. Not bad something as large and lux as an E-Class wagon.
Regarding E-Class wagons in general, for me, they are nigh unto paradise – even just so far as their relative sexiness and remarkable packaging are concerned. The cargo area is the epitome of easy flexibility with a completely flat floor and no intrusion into the space that might give away that this is any sort of hybrid with a lithium ion battery pack to accommodate. Space back there goes from 24.5 all the way to 68.9 cubic feet.
Acceleration to 62 mph is estimated at 7.8 seconds.
The 12-volt car battery has been moved to the rear of the car while the compact 55-pound lithium ion pack is placed to the right in the engine bay up against the bulkhead, thus putting all the "business" end of this deal up front. Using the equally compact 2.2-liter inline four-cylinder engine has certainly helped make this simplicity possible.
Thanks to the use of the 7G-Tronic Plus transmission, this little four gets some legs to cruise on, fifth gear being the 1:1 and sixth and seventh gears stretching out long. Our revs while cruising fast on no-limit sections of the Autobahn never exceeded 4,000 rpm. The tires are standard Continental ContiSportContact 5 – 245/45 R17 99Y – and they are not so hard that the typical Euro road sound shoots through the chassis to the base of one's neck. Acceleration to 62 mph for our chosen E 300 BlueTEC Hybrid T-Modell is estimated at 7.8 seconds and at 7.5 seconds for the sedan.
This is a big success for diesel hybrids and the entire system has an even larger future in store.
Given that the lithium ion pack is small and good for just 0.8 kWh of energy, the pure EV part of the equation is held to around 1,000 yards max and the integrated eDrive motor is good by itself up to 22 mph. Meanwhile, the eDrive cuts out totally at any speed beyond 100 mph. The 35-cell battery pack is constantly recharging due to engine deceleration and brake energy recuperation, but all of these actions are barely felt thanks to the added NVH work done to separate passengers from the under-hood goings-on. The software research done to smooth out the frequent off-and-back-on moments of the little four-cylinder has reached its apex in the E 300 BlueTEC Hybrid, so much so that it wasn't even a point of conversation all day.
This is a big success for diesel hybrids, and the entire system has an even larger future in store. With any luck (in a sense), things will get so bad with the cost of fuels that more people in the United States will be clamoring for hybrid diesels and stop whining so much about paying a premium for a luxurious and clean Mercedes that runs predominantly via a petite four-cylinder.
With well-designed diesel hybrid systems like this one from Mercedes, the hybrid market share might not level off quite so soon.
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