2014 Mercedes-Benz E250 is surprisingly smooth for a diesel ride

More power and lower emissions using fewer pistons is all the rage these days, and not just when it comes to gasoline engines.

Similar advancement of diesel-powered vehicles continues at a rapid pace and the 2014 E250 BlueTEC sedan is the latest example of the automaker's considerable experience in this field. Ultimately it's a car that can't be ignored by buyers with a taste for the Finer Things and a penchant for saving on fuel costs.

Mercedes-Benz first developed diesel-powered passenger cars back in 1936 and introduced them to the North American market 13 years later. Back then those noisy and somewhat odiferous beasts were low on power, although their highly efficient powertrains were considered unbreakable. Today, turbocharged diesel technology - also pioneered by Mercedes-Benz - is as clean as a proverbial whistle, while still offering the twin benefits of impressive fuel economy along with equally stellar get-up-and-go.

The E250 sedan is the latest example of M-B's diesel expertise. It's also the newest member of the wide ranging E-class family that includes sedans, coupes, convertibles, wagons, a gasoline-electric hybrid and a performance sedan that wears the AMG label. The E250 replaces the E350 turbo-diesel as the entry-point sedan for the 2014 model year. The outgoing car's 3.0-liter V6 was rated at 210 horsepower and 400 pound-feet of torque, while the E250's 2.1-liter four-cylinder compression-ignition engine delivers a still-decent 195 horsepower and 369 pound-feet of torque. But what's really decent is the E250's 28-mpg city rating and 45-mpg highway numbers that crush the 2013 E350 BlueTEC's 22/33 rating and the 2014 gasoline-powered E350 V6's 21/30 stats.

Connected to the turbo-diesel - in fact, to all E-class models - is a seven-speed automatic transmission.

Mercedes-Benz's latest 4MOTION all-wheel-drive system can be added as an option.

The BlueTEC part of the E250 name refers to AdBlue, which is a water-based solution that's injected just ahead of a special catalytic converter to clean up the exhaust gases. The AdBlue reservoir contents will last for about 10,000 miles and is topped up by the dealer, usually during oil changes. An instrument-panel warning light indicates when this service is required.

The twin-turbocharged four-cylinder is a stellar performer on many fronts. There's only a trace of typical diesel clatter at startup that completely disappears once under way. There's also plenty of punch when accelerating from rest or slow speeds, but that shouldn't surprise anyone given the engine's generous torque rating that peaks a low - and very usable - 1,800 rpm.

Mercedes-Benz's testing indicates a zero-to-60-mph time for the E250 in the low-seven-second range, which is an admirable number for any four-cylinder engine with the task of propelling a 4,400-pound sedan. Passing at highway speeds, the E250 isn't quite the tiger that it is around town, but it is by no means a white-knuckle experience.

In reality, the diesel performs so smoothly that you quickly forget about what's under the hood and simply enjoy the ride. The sedan's impressive stability at any velocity, combined with its ultra-comfortable and quiet cabin requires frequent monitoring of the speedometer to keep any flashing lights from suddenly appearing in your rearview mirror.

On the safety front, the optional Driver Assistance Package augments the E250's extensive standard content. This includes Distronic Plus with Steer Assist that helps the driver maintain a safe distance from the vehicle ahead. As well, a camera- and radar-based BAS Plus with Cross Traffic Assist watches for vehicles crossing in front and applies braking force, if necessary. The package's Pre-Safe Pedestrian Recognition can detect if a person has entered the car's path and can even apply the brakes if necessary. Lane Keeping Assist helps the driver stay between the lane markers, while Blind Spot Assist warns of vehicles approaching from either side.

Parking an E250 in your driveway starts at $52,300, including destination charges, which is about $500 less than the next-in-line E350 gasoline V6. That makes the most affordable and the most fuel-efficient E-class sedan a most tempting first-class ride.

2014 Mercedes-Benz E250

Type: Four-door, front- /all-wheel-drive sedan
Engine (hp): 2.1-liter DOHC four-cylinder, turbo-diesel (195)
Transmission: Seven-speed automatic
Market position: The number of diesel-powered vehicles in North America is rapidly growing as both luxury automakers and more mainstream companies add or expand their offerings. Lots of power and great efficiency.
Points: New E-class turbo-diesel significantly more fuel efficient than outgoing version; Great acceleration, especially from a full stop and when charging up freeway ramps; Impressive standard and available safety equipment; Seven-speed automatic transmission is silky smooth; Instead of paying a diesel premium, it's the cheapest E-class model.
Safety: Front airbags; side-impact airbags; side-curtain airbags; driver's knee airbag; anti-lock brakes; traction control; stability control.
MPG (city/hwy) 28/45 (RWD);
Base price (incl. destination) $52,300

By comparison:

Audi A6 TDI
Base price: $54,500
A 240-horsepower V6 with 406 pound-feet of torque is rated at 24/36 city/hwy.

BMW 535d
Base price: $57,500
2014 model uses 355-hp six-cylinder that makes 413 pound-feet of torque.

Volkswagen Passat
TDI Base price: $33,800
Uses a 140-hp four-cylinder making 236 pound-feet of torque.