It wasn't long ago that the majority of car buyers snubbed diesel-engine-equipped luxury cars. Not that we blame them. After all, who wants to shell out the big bucks for a righteous car that glides down the road as smooth as a hovercraft, has an interior that coddles and caresses, but has an engine that sounds like you're shaking a tin can full of rocks and smokes like someone is burning a tire in the trunk?
Fortunately, those days are long gone. As we all know, the modern diesel engine is a high-tech masterpiece that is enjoying a runaway resurgence in the mainstream. Due to some impressive engineering ingenuity, it has lost its high-decibel racket, as well as its notorious exhaust smoke. Finally, Rudolf's invention is once again finding its way into luxury cars, and we say it's about time.
We recently spent some quality time with the '06 Mercedes-Benz E320 CDI. To call this vehicle polished would be like saying that Mount Everest is a cute little hill. During our initial inspection, we were impressed by the impeccable fit and finish of the car, as well as the attention to small, but welcome, items (like covered trunk hinges) that make the trunk area flow visually when the trunk lid is open. As we slid into the creamy leather driver's seat, the door closed with little effort like the door latch was tenderly reaching out to grasp the catch. We feasted our eyes on Burl Walnut trim, and the Stone interior color made the car feel open, airy, and inviting. There is no shortage of technology in the E320 either. There are easy-to-understand, yet elegant dual-zone electronic climate controls, a nine-speaker Harmon/Kardon audio system with LOGIC7 surround sound, and a DVD navigation system. It would take 20 more pages to detail the scores (literally) of other high-tech devices that loom inside the E320, but we want to talk about the engine.
There are a lot of bells and whistles in the E320, but they're integrated into the design of the interior so as not to distract. There's also a battalion of safety items like dual front airbags, side airbags mounted front and rear, and a head-protection curtain. We found the front seats to be outstanding, with good support and just the right amount of bolster. The navigation system didn't have the detail we expected, but the nine-speaker Harmon/Kardon audio system filled the cabin with rich sound, so we didn't care if we were lost or not. | 
At highway speed, the CDI engine is imperceptible from an audio perspective. It's just there making ample power and generating great mileage. The E320 boasts a cushy ride, thanks in part to a four-link independent front suspension with AntiDive Geometry and an independent five-arm MultiLink rear suspension. | 
Our tester came shod with 225/55R16 all-season tires mounted on 16-inch dual-spoke light alloy wheels. Our only complaint about this car was the road noise that emanated through the cabin on certain types of asphalt. We think a better set of tires would help eliminate much of the din. |
The E320 is powered by a turbocharged and intercooled 3.2L 24-valve inline six-cylinder diesel engine. This powerhouse features a cast-iron block, aluminum head, common-rail direct injection (that delivers fuel at a pressure of 23,200 psi), dual overhead camshafts, and Bosch CDI electronic injection with pilot injection. Four hundred revolutions shy of its 4,600-rpm max engine speed, it makes 201 hp. The E320 produces a blistering 369 lb-ft of torque at only 1,800 rpm. The engine is mated to a five-speed automatic transmission that boasts Touch Shift and driver-adaptive shift logic. The engine lopes along at 1,600 rpm at 55 mph and 2,300 rpm at 75 mph.
Driving the E320 CDI is a lesson in refinement. It's clear that Mercedes engineers spent a considerable amount of time ensuring that the 3.2L CDI engine integrates seamlessly with the dignified E320. Diesel rattle is muted-more like nonexistent-throughout the engine's rpm range. When it comes to power, the engine hauls the 3,835-pound sedan with authority. There is no perceptible turbo lag, and during hard acceleration the engine generates the sound and pull of a small-block V-8. No kidding. As a matter of fact, Mercedes says that the E320 sprints from 0-60 in 6.6 seconds, which is only one-tenth of a second behind the gasoline V-6-powered E350. Then there's the E320's mileage. Hold onto your cognac, because the E320 is rated at a darn respectable 27 mpg city and a whopping 37 mpg highway. This translates to a Docker-creasing cruising range of about 777 miles, thanks to the E320's 21-gallon fuel tank. Our test tank of fuel returned 26.9 mpg. We think this is pretty darn good considering that this figure represents mostly city driving and our notoriously heavy right foot.
By the time you read this, Mercedes will be poised to unveil the new '07 E320 CDI that is powered by a new BLUETEC diesel V-6 (see sidebar). Now might be a great time to beat feet over to your Mercedes dealer and see if you can score a deal on a '06 before they're all gone.