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Mercedes-Benz E320 Bluetec Review

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Mercedes-Benz E320 Bluetec

Performance and luxury are not incompatible. There is no shortage of vehicles which combine high levels of both, in any form imaginable. But add fuel economy to the mix, and the list gets mighty short. Such a vehicle would have to be a hybrid, right?

Not necssarily. Hybrids, as currently implemented, are most economical in traffic. In other words, they are at their best in the worst driving conditions. At highway speeds, their gasoline engine does most of the work, and since the engine in most current hybrids is relatively small, it works hard, and real highway mileage can be less than the advertised. So how to best combine luxury, performance, and fuel economy on the open road - particularly the open, no-speed-limit Autobahn?

With diesel power.

No joke. In Europe, the majority of luxury cars are diesel-powered. And modern diesels are not the rattly, noisy, smelly, smoky things of the past. They are smooth, quiet, and refined. An excellent example is the new Mercedes-Benz E320 Bluetec.

Nowhere outside does it say "diesel." There is a subdued, and very quiet, diesel sound audible from outside at idle; in the cabin all is quiet. At highway speeds, the Bluetec is just as quiet inside as a gasoline-engined car. During my week's test, I saw a highway average of 35 mpg, at realistic (read 70 mph+) speeds, not the EPA simulated 50. Around town, low 20s, where a similarly-sized gas-powered car would get five mpg less. In mixed city, backroad, and highway driving, about equal parts of each, 27.

All of this with no power shortage, even at highway speeds. The 3.0-liter turbodiesel has 208 horsepower, about the same as a 2.5 to 3.0-liter gasoline engine. But torque, not horsepower, is what accelerates a vehicle, and here diesels rule. The Bluetec's 388 lb-ft compares not to a three-liter gasoline engine, but to a five- or six-liter high-performance gasoline engine. That, and a seven-speed transmission, helps it achieve a zero-to-sixty time of 6.6 seconds, competitive with many sports sedans.

"Bluetec" is DaimlerChrysler's name for its clean diesel technology. It reduces the nitrogen oxide and particulate emissions that have been the bane of diesel engines. As implemented in the E320, an oxidation catalytic converter and particulate filter are combined with an NOx trap and SCR catalytic converter to meet the most stringent standards now in place. Because of the catalytic converters and filters, ultra-low sulfur diesel fuel must be used, and it has only recently become available in the U.S. If all of this sounds familiar, congratulations - it's analogous to the time when lead was removed from gasoline, and catalytic converters installed. At this time, the E320 Bluetec is a 45-state car, but it can and will be further developed to please even the California Air Resources Board and become available in states that adhere to California emissions standards.

It will be worth the wait, if my week with the E320 Bluetec is any indication. The car combines all of the style, luxurious comfort, and refinement of the current Mercedes-Benz E-Class with quick acceleration and excellent fuel economy. It started promptly, with no long wait, idled quietly and smoothly, and, except for the lower fuel consumption, was little different from a gasoline-powered E350 with the same options. A 200-mile mostly highway day was a pleasure, made even better by seeing 35 mpg on the trip computer.

APPEARANCE: The distinguishing features of the E320 Bluetec compared to its gasoline-powered siblings? "BLUETEC" in small chrome letters on the right side of the rear panel. Other than that, it has the same smoothly-sculpted shape, the same four-eyed face, the same freestanding three-pointed star hood ornament, and the same large wraparound taillights as any other current E-Class model. With the full-length Panorama sunroof, the top looks black.

COMFORT: Inside as well, the Bluetec is indistinguishable from its gasoline-powered siblings in styling and appointment. My test example had the standard "MB-Tex" synthetic, which looks and feels more like leather than some leathers. Seat comfort is superb - this is a car meant for serious distance - and both front and rear accommodations are first class. The standard equipment level is appropriate to its price point, and key options including the dual panorama sunroof and the "Premium II Package" option group with, among other items, DVD/gps navigation system, Sirius satellite radio, heated front seats, hands-free communication for an approved cell phone, and bi-xenon active headlamps. It also includes the "KeylessGo" system, in which the electronic SmartKey need not be inserted into its dashboard receptacle. The CD changer plays MP3 as well as regular CDs.

SAFETY: The E320 Bluetec's chassis structure is built with a steel safety cage around the passenger compartment, with front and rear crumple zones adding further protection. Dual front airbags are supplemented by side bags for both front and rear seats, and side head curtain airbags. Four-wheel antilock disc brakes are aided by brake assist and the ESP electronic stability program.

RIDE AND HANDLING: The E320 Bluetec's natural habitat is the open highway, preferably at Autobahn speeds. It is optimized for this with a solid structure and fully-independent multilink suspension tuned firmly enough for high-speed control but supple enough for long-distance comfort. The structural design and judicious use of soundproofing materials, and attention to aerodynamic detail, keeps the interior noise level very low, even at high speeds. It's more of a luxury sedan than a sports sedan, but it handles quite capably on entertaining roads, and can move down them as quickly as some alleged sports sedans.

PERFORMANCE: If your concept of diesels is slow and smoky, you need to be brought into the 21st Century. The E320 Bluetec is neither. The turbocharged and intercooled 3.0-liter V6 engine is made of aluminum alloys for light weight, with cast iron cylinder liners. The combination of high-pressure electronically-controlled common-rail direct fuel injection and the Bluetec catalysts, particulate filter, and NOx trap makes it burn cleanly and efficiently, for improved fuel economy and low emissions. Because of their high compression, diesels produce great amounts of torque, and the E320's is a fine example, with 388 lb-ft on tap from 1600 through 2400 rpm. No, that wasn't a misprint - and it can be felt readily when the accelerator is pushed. No smoke, no smell, only a little noise when cold, and fast starting - what's not to like? The power gets to the rear wheels via Mercedes-Benz's seven-speed automatic transmission, a wonderful unit that is as smooth as expected for a luxury application, shifts smoothly, has computer control logic that adapts shifting to the driver's driving style, or can be shifted manually. It helps improve both acceleration and economy.

CONCLUSIONS: The 2007 Mercedes-Benz E320 Bluetec shows that diesels can be quick, quiet, and supremely economical in operation.

2007 Mercedes-Benz E320 Bluetec

Base Price			$ 51,550
Price As Tested			$ 58,835
Engine Type			dual overhead cam aluminum-alloy V6 with
				 cast iron cylinder liners,
				 electronically-controlled common-rail
				 direct fuel injection
Engine Size			3.0 liters / 182 cu. in.
Horsepower			208 @ 3800 rpm
Torque (lb-ft)			388 @ 1600-2400 rpm
Transmission			7-speed automatic with adaptive shift
				 logic and TouchShift manual mode
Wheelbase / Length	                   112.4 in. / 191.0 in.
Curb Weight			3860 lbs.
Pounds Per Horsepower		18.6
Fuel Capacity			21.1 gal.
Fuel Requirement	                  ultra-low sulfur diesel
Tires				P225/55 HR16 Michelin Energy mxv4
Brakes, front/rear	                  vented disc / solid disc, ABS, BAS,
				 ESP standard
Suspension, front/rear		independent 4-link, independent 5-link
Drivetrain			front engine, rear-wheel drive

EPA Fuel Economy - miles per gallon
    city / highway / observed		26 / 37 / (20/35)
0 to 60 mph				6.6  sec

Iridium silver paint				$   700
Panorama sunroof				$ 1,000
Electronic trunk closer				$   520
Premium II package - includes:
  DVD navigation, Sirius satellite radio, heated front
  seats, power rear-window sunshade, hands-free
  communication system, Keyless Go, bi-xenon
  headlights with active curve illumination, headlamp
  washing system				$ 4,290
Destination and delivery			$   775