Bluetec: A red-hot diesel burner

These days, a certain feeling of dread accompanies me to the gas pump.

As you may have noticed, manufacturers like to send us their most powerful vehicles for testing. With the rising cost of fuel, the $50 fill-up has become frighteningly commonplace.

So I was pleased recently to find myself approaching the pumps with a forgotten spring in my step.

It was final day of my weeklong test of Mercedes-Benz’s new diesel-powered E320 Bluetec sedan, and the fuel gauge had yet to hit the three-quarters mark.

That’s enough by itself to make a guy feel better about slipping his card into the slot — but it gets better: diesel that day was selling for a full dime less than the lowest grade of gasoline.

Double score.

At $52,000 and change, the E320 Bluetec is too pricey to be the Prius of the diesel movement. But it is a harbinger; its arrival in the U.S. signals the ascent of diesel as a viable alternative to gasoline.

In Europe, where high fuel prices are a fact of life and diesel enjoys significant tax advantages, 50 percent of all new cars sold are diesel-powered. U.S. consumers traditionally have written off diesel as noisy, smelly and underpowered.

The E320 Bluetec puts the lie to all three objections.

Bluetec is M-B’s new clean-diesel technology and the E320 Bluetec is the only diesel-powered passenger car available in the U.S. in 2007 (as opposed to trucks, which operate under a different set of regulations).

Designed to burn the low-sulfur diesel that arrived at pumps last October, it’s clean enough to satisfy emissions standards in 45 states, including Washington and Idaho. Once M-B and regulators agree on how to implement the final stage of the Bluetec process (it involves “scrubbing” the exhaust with a chemical called urea), it will be the country’s first 50-state diesel solution.

In 2008, we will begin seeing a variety of diesel offerings, most from Europe, but with a likely smattering of Japanese entrants, as well.

Bring Da Noise. Not.

I was deep into my test week when I first detected a faint hint of the familiar diesel rattle. It occurred only at low rpm and under light throttle pressure — and I had to listen hard to hear it.

Neither was there ever any scent of diesel, either from inside the car or outside it. Ditto the obnoxious blast of blue exhaust so familiar to the diesel driver.

Clean diesel really is clean.

As anyone who has ever owned a diesel knows, the technology is notorious for its sluggish performance. That concern was resolved when turbocharging was first applied to diesel, an application that is now pervasive.

In the case of the E320 Bluetec, a turbocharger cranks up the power at about 1,600 rpm and enables the 3.2-liter V-6 to pump out 208 horsepower and a massive 388 pound-feet of torque.

The diesel engine has a narrow power band – peak torque ranges only from 1,600 to 2,400 rpm – and it redlines at just 4,300 rpm. Fortunately, M-B happens to have a very good seven-speed automatic transmission, which has been calibrated to keep the engine in its sweet spot.

Accustomed to gauging power in terms of ponies, many Americans will miss the salient point: this diesel is strong. In fact, its 0-60 sprint time is just one-tenth of a second off the time recorded by the gasoline-powered version of the E320.

There is a performance downside: below 1,600 rpm, where there is little power, the transmission is slow to kick down into a lower gear. Consequently, the Bluetec is not squirty-quick in traffic.

Under the same conditions, and with a cold engine under light throttle, the first-to-second upshift is jerky and ragged. The best solution: put your foot into it.

The Pay-off

Fortunately, even an aggressive right foot cannot undo this engine’s thrifty nature. It earns an EPA rating of 26 city/35 highway.

The Bluetec-equipped E320 Mercedes costs just $1,000 more than the standard E320.

With fuel prices at their current levels, that spread would be covered in 40,000 miles of driving.

That gives diesel an advantage over more expensive hybrid technology, with its longer amortization period. Nor does diesel require the complicated electronics of hybrid technology — or the energy-intensive production of battery packs.

And, with the emergence of bio-diesel, the technology can even divorce itself from the consumption of fossil fuels.

A True Win-Win

The Bluetec edition of the E320 sedan is true to the original, complete with all the amenities expected of a midsize luxury sedan.

For 2007, the E320 family has been updated with a new front-end design, implemented largely to improve aerodynamics and, hence, fuel-efficiency. New, industry-leading safety measures are included, along with all the familiar M-B virtues, including one of the best interiors in the business, a terrific ride and handling package and the unmistakable prestige of the three-pointed star.

Price will limit its sales, but the E320 Bluetec is proof that good sense and good driving are compatible seatmates.