For a moment, I forgot I was at the entrance to a wide, empty, highway slicing through a sparsely populated section of New England countryside. It is a stretch of freeway frequently used by motorists who want the opportunity to test the limits of  high performing vehicles – or just to have a bit of fun on the wrong side of the posted speed limit.

Normally, this is the point where I floor the accelerator and see what the sports car of the week can do. But inside the Mercedes E-320 Bluetec, there is a tendency to ignore the passing world, to sit back in the soft, heated leather bucket seats which, seemingly, were sculpted by the luxury recliner makers at La-Z-Boy and absorb the bass lines from Big Muff into a melodic body massage.

But the guy in the Mustang behind me was in a hurry, so I floored the accelerator and the turbocharged diesel engine hummed into life.  The E-320 has only a V-6 engine which cranks out a just 208 horsepower – normally a fairly anemic power plant for a sports car.

But this is a turbocharged diesel engine, which is more responsive than the conventional gasoline model, and acts more like a conventional V-8. In addition, the Bluetec’s engine operates with a boosted torque rating of 400 – a level you are more likely to find in a Corvette.

As a result, response in the luxury sedan is virtually instantaneous. And hitting the accelerator kicked the sports sedan effortlessly through its seven speeds till the Connecticut countryside slid by in a 130 mile an hour green blur. Approaching a wide curve in the highway I changed from automatic to manual mode, downshifted and guided the Bluetec effortlessly from the outer lane to the tighter, inside lane and then continued running through the forest. Mercedes doesn’t make bad sports cars, and this one holds the road as well as any of the higher priced racers.

The MercedesE-320 is a well laid out sedan providing the performance and appointments you’d expect in a $60,000 luxury, mid-sized sedan. Diesels have not been prominent on American highways, accounting for only about 4 percent of nation’s autos though they comprise more than half the cars roaming European roads.

The diesel is a more fuel efficient engine – the E-320’s Bluetec gets an estimated 37 highway miles per gallon – about 40 percent more fuel efficient than a comparable gasoline V-6 engine. In addition, the diesel engine is far more responsive and powerful than its gas cousin.

Mercedes’ Bluetec diesel is also among the cleanest, already meeting the U.S. standards for emissions which are not slated to go into effect until 2009.

Outside, the E-320 has the sleek, ready-to-spring look characteristic of Mercedes sports cars. It is one of those vehicles which looks as if it is in motion while sitting still.  Inside, its two tone leather seats and finish are offset by the walnut wood veneer on the doors, dash and center console.

The double curved dash has a gentle swell in the center holding the information console and neatly dividing the dash into separate spheres with each front passenger getting their own space. It gives the illusion that you are in a larger sedan. This is not a sports car limited to short people, either. There is plenty of room in the rear for a pair of average sized adults while the front has room for the average NBA giant.

As you might expect in a luxury car, the E-320 comes with an easy-to-use, DVD-based navigation system, as well as AM/FM and Sirius satellite radio. For entertainment, there is an in-dash, six-disc CD and MP3 player utilizing a Harmon/ Kardon Logic-7 sound system which can either envelope the interior in sound or, if you open the windows and crank open the sunroof, serve as the boom box for the average block party.

It’s a sports car that is as environmentally efficient as a hybrid, as responsive as a Porsche, and invites you to find an open road and just go.

2007 Mercedes E-320 Bluetec

MSRP:       $58,375
EPA Mileage:   26 MPG City   37 MPG Highway
As Tested Mileage:      28 MPG Mixed

Performance/ Safety:

3.0-Liter turbocharged, aluminum V-6 engine producing 208 horsepower and 400 pound-feet of torque; 7-speed automatic transmission with touch-shift manual mode; rack and pinion steering;  4-wheel independent suspension; electronic, power-assisted, 4-wheel vented disc brakes with anti-lock and brake assist; traction control and roll over sensors;16-inch dual spoke alloy wheels; dual front airbags; front and rear side and curtain airbags.

Interior/ Comfort:

AM/FM/ Sirius satellite radio; 6-disc, in-dash CD and MP3 player; Harmon/Kardon Logic-7 sound system; DVD-based navigation system; power tilt/sliding sunroof/ power tilt/ telescope leather wrapped steering wheel; Bluetooth communications system.

To read more about Stylish, Fast, Efficient and Clean: The Diesel and the Sports Car see Stylish, Fast, Efficient and Clean: The Diesel and the Sports Car in the USBE News archive.