2014 Mercedes-Benz E250 BlueTec (pictures)

The 2014 Mercedes-Benz E250 BlueTec is a big, almost sinister looking sedan, particularly when equipped with its more aggressive Sport package.

But beneath its hood is an engine that is anything but sinister; the BlueTec powertrain is actually quite thrifty.

Displacing just 2.1-liters, the four-cylinder diesel engine outputs about 369 pound-feet of torque with the help of its two turbochargers.

That torquey engine is mated to a smooth shifting 7-speed automatic transmission.

Power then flows through the rear wheels in the standard configuration or a 4Matic all-wheel drive system, which is optional.

With the aid of an auto stop-start system, the naturally fuel efficient diesel is able to do an estimated 28 mpg in the city and 45 mpg on the highway.

Ours was equipped with a no-cost Sport package upgrade, which features a more aggressive front bumper and grill treatment.

The suspension also gets a dose of 'sport tuning' with a firmer ride and slightly lower ride height.

The Sport package wheel retain the same 17-inch diameter as stock, but feature a design that is unique to the package.

A $1,500 Lighting package replaces the headlamps with full LED arrays that steer into turns and automatically dim their high beams when other vehicles approach.

Tail lights are LEDs regardless of packaging.

Despite its "sport tuning," the Benz was a smooth rider. Though bumps in the road were noticeable, they weren't pronounced or jarring at all.

The cabin is a nice place to sit, which you'd expect from a sedan that starts at $51,400 and then adds $1,620 for leather and wood trim.

The Mercedes-Benz dashboard suffers from no shortage of buttons, which is good. You'll need these shortcuts to quickly navigate the at times confusing COMAND infotainment system.

Our vehicle also included a $450 option for ventilated seats (heated surfaces are standard) and $660 for a massaging driver's seat with active bolstering. You bottom will thank you.

The COMAND controller is a simple device. It can be twisted, pressed, and nudged in four directions. I also like the shortcut buttons flanking the knob.

However, I've no love for the COMAND on-screen interface, which can be confusing, poorly organized, and difficult to use at speed.

An LCD in the instrument cluster can be configured to display a variety of information relative to driving efficiency, safety tech, navigation, or the current audio source.

The true hallmark of any luxury vehicle is the analog dashboard clock -- never you mind that digital clock located just inches away on the central LCD.

I was surprised to see a 30-pin connector in our brand new Mercedes-Benz. You'll have to bring your own Lightning-to-30-pin adapter to use newer iOS devices. Android users can make use of the standard Bluetooth audio streaming.

The Harman Kardon audio system sounded fantastic. With simple tweaks, it could be bass-heavy for electronica and hip hop, crisp and clean for more delicate genres, or loud and clear for a bit of Led Zepplin.

Navigation is powered by an 80GB internal hard-drive. The maps look pretty good, but I had to talk to the voice command system like a child to get it to understand me.

Our vehicle also featured the automaker's Parking Assist system, which can automatically parallel park the Benz. I found the system to be great when it works, but tricky to access.

This diesel-powered variant of the 2014 Mercedes-Benz E-Class may not be as powerful as the competition from Audi and BMW, but it's more efficient and no less capable in real world driving. It's too bad that the tech is so awkward.