Mercedes-Benz E320 CDI puts a new twist on the diesel design
Bob Plunkett
Date Posted: 5/10/2005
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SAN ANTONIO, Tex. -- Among automobile powerplants containing internal combustion chambers, the pressure-ignited heat engine named after German inventor Rudolf Diesel is considered most efficient for burning fuel and translating the resulting energy into linear movement.
But it was Mercedes-Benz of Germany that built the first passenger car powered by one of Diesel's engines -- the 260D of 1936.
Actually, the history of Mercedes is marked by many diesel-powered vehicles, and as late as 20 years ago the majority of all cars with the tri-star Mercedes marque shipped to America packed a diesel-type engine.
Yet sluggish performance figures in combination with sooty emissions and obnoxious belching noises from diesels soured the concept for consumers in the United States, and Mercedes pulled its last diesel car from North America after 1999 and the E300 TD.
Now click the fast-forward switch to today's time zone and you'll find that engineering wizards at Mercedes have developed a new generation of diesel engines which generate surprisingly quick acceleration times while producing low exhaust emissions and superior fuel economy scores.
That leads us to the 2005 E320 CDI, a new diesel-powered version of the mid-size E-Class luxury sedan by Mercedes available now in 45 of the 50 United States.
This E-Class diesel totes a 3.2-liter six-cylinder engine of in-line arrangement with a twin-cam design incorporating common-rail direct injection (CDI) and multistage turbo-charging through a variable nozzle turbine (VNT).
The CDI unit amounts to a fuel line loop which delivers a constant supply of combustible fuel under extremely high pressure to each of six injector valves, one for each cylinder. And using electronic fuel injection means the CDI engine can be cleaner and stronger -- and far less noisy -- than previous diesels using mechanical fuel injection.
In the E320 the six-pack plant produces 201 hp at 4200 rpm plus substantial torque of 369 lb-ft available at only 1800 rpm.
It's rated to earn fuel economy scores well above 30 mpg for highway cruising and, when tied to a fuel tank of 21.1 gallons, puts the cruising range out at 700 miles or more -- which far exceeds any passenger's cruising range without inserting a rest stop.
Track times indicate the E320 CDI can accelerate from a standing start to the mark of 60 mph in 6.6 seconds, while the top speed, limited by electronics, is 130 mph.
And E320 CDI runs so quietly and provides such juicy acceleration, particularly in lower gears, that a driver would never suspect there's a diesel engine aboard without checking the label.
Our turn to drive the E320 CDI comes in a contest to determine precisely how little fuel is required to propel a vehicle weighing almost two tons over a course of 108 miles charted through the Texas Hill Country.
So seal off the fuel tank (so no one cheats by adding fuel along the way), then steer the E320 CDI with a light foot on the go-pedal along Texas 1340 North and Route 41 East to Kerrville before climbing on the I-10 slab and shooting off to San Antonio for a finish line downtown on Crockett Street.
At that terminal point, the car's fuel tank is opened to determine how much fuel is consumed during the drive.
We find that our car burns 2.42 gallons of fuel, which works out to 44.6 miles per gallon along the course.
And, other than using a gentle touch for take-offs and running perhaps 10 mph lower than posted speed limits on highways, we did not resort to unusual tricks to conserve on fuel -- such as switching off the air conditioner on a rather warm day or attempting to tuck in close behind big-rig trucks on I-10 in the manner of race-car drafting.
However, those in this contest who employed such tactics earned even higher numbers -- some over 50 mpg.
Park the E320 CDI beside a gasoline-powered E320 and you cannot detect any difference between the two cars.
Styling for both includes a dramatic face framing windswept lines running from the low-cast prow to a high-hiked tail through an arching profile with coupe styling on the roof due to blacked-out center pillars.
A pentagonal grille in chrome flanked by pairs of articulated oval headlamps marks the face unmistakably as a Mercedes, but it's raked and streamlined to match smooth lines sweeping rearward.
So much streamlining works for this package, in fact, that it's one of the most aerodynamically efficient production cars in the world.
The canted hood and bulging fenders incorporate striking curves of the headlamps and extend them rearward in taut lines. Stylists from Mercedes say these lines were inspired by human anatomy and the smooth ripples compare to toned muscles on an athlete.
A five-seat passenger compartment draws on fine leathers and rich polished hardwoods with climate controls for four separate zones.
High-tech Mercedes options are available for this car such as Distronic adaptive cruise control, multi-contoured Drive Dynamic seats, a twin-window Panorama sunroof and bi-xenon headlamps linked to point-around-the-curve illumination, and a DVD-based navigation system.
The navigation system integrates a guidance system with Global Positioning Satellite (GPS) reckoning and hands-free telephone and audio controls. A driver can interact with this intelligent system and use it to control the audio, dial phone numbers or figure out where to go.
Transmission for the CDI turbo-diesel is the impressive Mercedes five-speed automatic, which brings one-tap clutch-less shifts through a TouchShift stick.
Like other E Class models, the E320 CDI includes electronic brakes in a brake-by-wire system labeled Sensotronic Brake Control (SBC).
And there are devices aboard to stabilize the vehicle's forward movement and tire traction.
Sensors set in the suspension system determine vehicular payload, speed and road conditions, and they can adjust dampers on shock absorbers to smooth out or firm up the ride quality.
In addition, the E320 CDI carries multiple air bags to cushion the human cargo including curtain-style air bags concealed in headliners above side windows which will deploy in the event of rollover movement.
Pricing for 2005 E320 CDI begins with the MSRP of $49,795.
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| 2005 MERCEDES BENZ E 320 CDI VEHICLE SPECIFICATIONS |
| Description: |
Mid-size luxury sedan |
| Model Options: |
Mid-size luxury sedan |
| Wheelbase: |
112.4 inches |
| Overall Length: |
189.7 inches |
| Engine Size: |
DOHC 3.2-L I6 CDI VNT |
| Transmission: |
Auto/5/TouchShift |
| Drive: |
Rear |
| Braking: |
Power 4-disc ABS/BA/EBP/ASR/ESP |
| Airbags: |
2 (front), 2 (side), 4 (side curtain) |
| Gas Mileage: |
27/37 mpg |
| MSRP Price: |
$ 49,795 |
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