To some folks, putting a diesel engine into the latest generation of the iconic Mercedes-Benz S-Class is akin to having cell phones ringing at a funeral.
To others — and the Mercedes folks feel that will be between 5 and 10 percent of S-Class buyers — the reaction is, “It’s about time to have a diesel option.”
The present generation S-Class flagship of the M-B lineup has been around since 2006, an extraordinarily long life in “automotive years.” However, it’s still the segment leader and many would argue it reigns as the finest automobile made.
The diesel engine, introduced by Rudolf Diesel in 1893, first went into volume production with Mercedes in 1936 with the 260D as a 2.5-liter engine with 45 horsepower. (We can’t give you a 0-to-60 time because its top speed was 59 miles per hour). In 1977, Mercedes came out with the 300SD, the first production turbo diesel. That vehicle was notable for two things:
It was, in automotive terms, nearly indestructible given minimal maintenance.
It demonstrated all the negatives many people still associate with diesels. It clattered, belched blue smoke, deposited a sooty coating on the back of the car, and left a dirty exhaust smell in its wake.
Due to more stringent US tailpipe regulations versus those in Europe, Mercedes then phased out the diesel after the 350SD in 1995.
But now it’s back. Passersby near the Mandarin Oriental Hotel on Boylston Street were ogling a line of S-Class sedans parked in the valet area one late October afternoon. They didn’t look any different from the most common S-Class sedan — the S550 4Matic (all-wheel-drive) — other than the S350 badging.
However, there’s a big difference under the hood. The S350 BlueTEC is powered by a 3.0-liter V-6 turbodiesel that produces a modest (for that size car) 240 horsepower but a whopping 455 lb.-ft. of torque — the amount of twisting force available to turn the wheels.
The BlueTEC diesel exhaust system uses an oxidizing catalytic converter and particulate filter before breaking gases down into nitrogen and water vapors by injecting Adblue, a urea solution, into the tailpipe. The Adblue is stored in a seven-gallon tank accessed under the spare tire and needs refilling at approximately 10,000-mile intervals. Mercedes emphasizes that both the diesel and new S400 Hybrid variants contain the same interior room, luxury and convenience accoutrements as all S-Class vehicles.
Boston.com’s Cliff Atiyeh joined me for a drive around an in-town loop—one that covered a similar course as the annual Tufts 10K Columbus Day women’s road race. I headed for a blue sedan with camel interior, but Cliff motioned to a silver one instead. A good choice. It had a stunning deep cocoa and black leather interior package that was the equal of any interior I’ve ever seen, especially with the white-on-black electro luminescent S-Class gauges.
You had to be listening closely — with the $6,400 Bang & Olufsen BeoSound audio system turned off — to hear just the hint of engine clatter on a few occasions when the engine lugged slightly. We saw no smoke in the mirrors or from the other test S-Class diesel sedans on the road, though we did notice mild turbo lag when jumping hard on the throttle.
Power goes to all four wheels through an advanced seven-speed automatic transmission that’s designed to work with a low-viscosity, low-friction transmission fluid (colored blue instead of red).
Mercedes’ Eric Linder, assistant product manager for the S-Class, said the diesel should return 21 miles per gallon in city driving, 31 on the highway, and 25 combined. And this M-B diesel does have a 0-to-60 time: About 7 seconds.
If there’s a downside, it’s that you’ll need a long sit-down lesson with your salesman in order to figure out all the controls. Linder feels there’s a knowledgeable customer base with experience in prior M-B diesels, a group that’s been waiting for a car such as this.
Pricing on the S350 starts at $92,550, $4,950 below the price of the best-selling S550 4Matic. And a diesel, with care, should run just a few miles short of forever.
Bill Griffith can be reached at WGriffith@globe.com.
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