I'll cut to the chase. The 2014 Mercedes-Benz E250 BlueTec is brilliant and it mostly has its engine to thank for it.
Under the hood, you'll find a relatively small (for a vehicle of this size) 2.1-liter twin-turbodiesel four-cylinder. Output is stated at 195 horsepower, which is decent when compared to the similarly-sized Honda Accord's 185 ponies from its 2.4-liter engine. With a relatively low redline, it's no surprise that high-revving horsepower isn't the diesel's strong suit, so we instead turn our attention to the stated 369 pound-feet of torque, which is impressive no matter how you slice it.
That engine is mated to seven-speed automatic transmission, the only gearbox option for the E250 BlueTec, which then sends power to the rear wheels. Drivers can option Mercedes' 4Matic all-wheel-drive system, which should slightly improve sure-footedness in slippery conditions, but the rear-wheel-drive configuration is certainly the more fuel-efficient of the two configurations. And fuel efficiency is indeed one of this power train's strongest features.
According to the EPA, the rear-driven variant of the E250 BlueTec is good for 28 mpg in the city, a very decent 45 mpg on the highway, and 34 mpg combined. The 4Matic equipped model drops down to 27 mpg and 42 mpg in the city and on the highway, respectively.
Also helping fuel economy is an auto stop-start system that shuts down the engine while the vehicle is stopped (say, at a traffic light) to reduce fuel wasted to idling. I found the system to be smooth and unobtrusive and I appreciated the extra quietness of the cabin while stopped. By the time I could casually get my foot from the brake pedal to the accelerator, the Benz was fired up and ready to roll. If you're more of a lead footed driver, the system is easily defeated with the press of a dashboard button.
My actual numbers for testing were a bit lower than the 34 mpg combined estimate, likely due to a variety of reasons: I spent a lot of time testing the driver aid tech in heavy traffic; the vehicle spent hours idling while we produced the video at the top of this review; and I couldn't help matting the accelerator more often than was absolutely necessary to sample the torquey diesel performance.
Driven like a sane person, the E250 BlueTec was remarkably comfortable. The diesel engine was very quiet, the shifts of the seven-speed automatic were imperceptibly smooth, and the suspension was supple, even with the no-cost upgrade to the Sport package's sport-tuned suspension. The ride wasn't so supple that you wouldn't notice the bumps in the road or rough patches of asphalt, but I was never jarred by the bumps, and the ride was never harsh.
With so much torque available from quite low in the tachometer's sweep, the engine was both responsive and effortless. When I needed a bit more grunt to make a pass, there was no need to wait for the transmission to downshift, the acceleration was nearly instantaneous and linear.
Asking for a dramatic change in velocity -- say, stabbing the accelerator when cruising at 25 mph -- isn't nearly as instantaneous. Turbo lag, while slight and only momentary, is noticeable and the smoothness of the transmission's shifts becomes a liability where snappiness is concerned. But there's the slight whistle of the turbos spinning and the steady press of acceleration on the other side of this brief hesitation, which makes it worth a moment's patience.
Even with the torque going to the rear axle and the Sport package's suspension and appearance upgrades, the E250 BlueTec is no sports car. It's more of a powerful Grand Tourer, much more comfortable on the highway where its high-speed stability and supple suspension can do their thing.
Dated dashboard tech
I'll also cut to the chase where the Benz' dashboard tech is concerned: The COMAND infotainment system is terrible, probably the worst in class at this point. I won't belabor the point, because we've been down this road many times before, but the system's weird three-tiered organization of on-screen options and occasionally inconsistent treatment of the physical controller are still alien and frustrating to me, despite having used some iteration of the command scheme for almost six-years now. No, sir, I don't like it.
Fortunately, beneath the dashboard display is a massive bank of physical buttons with shortcuts for navigation, disc (which can be tapped multiple times to cycle through the many digital media sources), radio, telephony, and more. I'd suggest you use these quick shortcuts for navigating rather than fooling with complicated and many-layers-deep interface of the COMAND system.
The list of audio sources is, thankfully, more complete than most, and the optional Harman Kardon surround sound audio system is equally impressive. Standard sources include a six-disc in-dash DVD changer, Bluetooth hands-free calling and audio streaming, USB connectivity for mass storage devices, an auxiliary input, an SD card slot, and a 30-pin iPod connector. Users of newer iOS devices that use the Lightning cable will need to purchase a lightning to 30-pin adapter -- according to Editor Wayne Cunningham's testing in the contemporary CLA250, simply plugging into the USB port won't work -- which is a black spot on the otherwise solid list of standard audio sources.
Our vehicle was equipped with an optional $3,870 premium package that adds an 80GB hard drive-based navigation system (with 10GB dedicated to music storage), which isn't really worth the money, and the aforementioned Harman Kardon premium audio system, which is definitely worth the bucks. Audio quality is strong and balanced. Bass response isn't as bold as some of the other Harman Kardon systems that I've tested recently, but the entire system benefits from being better-suited for almost any genre of music, rather than targeting the thumpier, boomier characteristics of pop, hip-hop, and electronica. Don't get me wrong, you can still fill the cabin with the wub-wub-wub of dubstep should you want to, but you can also enjoy more delicate passages as well thanks to clear highs and mids.