Drive long enough through the lush green environs in and around Portland, Oregon, and you’re bound to encounter more than a few big rigs hauling impossibly huge stacks of cigar-shaped logs in giant steel humidor cages and spewing tell-tale clouds of thick black diesel particulate matter. When you pass one in a cutting-edge clean-diesel car like the 2014 Mercedes-Benz E250 Bluetec sedan, it serves as a stark reminder of how far diesel-powered passenger cars have come, and how far diesel must go to stay relevant in an increasingly green automotive future.
One of the unquestioned advantages of diesel — and why it has become ubiquitous for massive long haul trucks — is the mileage/range advantage over gas-powered engines. In Europe, where stratospheric fuel prices have been the norm for decades, diesels have become a major segment of the market. For example, Mercedes offers all manner of diesel-powered options for the newly updated 2014 E-Class in the Old World.
Here in the U.S. the options are much more limited. But the Europeans have been carefully re-establishing a diesel beachhead, and Benz has been on that front line. The 2014 E250 Bluetec is the latest U.S.-market E-Class to be offered by Mercedes in the modern passenger-car diesel era, and not surprisingly, the automaker says it’s more efficient than ever.
Powering the E250 is Benz’s relatively new all-aluminum 2.1L, in-line four-cylinder twin-turbo diesel mill (it’s also available in the GLK250 crossover), which replaces the 3.0L six that generated 210hp and 400 lb-ft of torque that propelled the outgoing E350 Bluetec. While not quite as powerful as the six at 195hp and 369 lb-ft (peak torque is available from 1600-1800rpm), Benz officials insist the 2.1L will perform at least as well as the 7.5sec 0-60mph and the 15.6sec quarter-mile a 2011 E350 Bluetec sister publication Motor Trend tested achieved back in 2010. A GLK Motor Trend just tested with the same engine as the E250 hit 60mph in 7sec flat and 15.3sec in the quarter. We expect similar numbers from the E-Class diesel. Benz also added two balance shafts to the engine to help minimize the vibration characteristic of in-line fours in an effort to deliver the type of smooth power delivery E-Class buyers have come to expect.
How can the E250 achieve the same acceleration with less overall power? Mainly thanks to a twin-turbo setup that utilizes a small high-pressure turbo mounted at the exhaust manifold in order to deliver higher boost at lower engine revs. A larger, low-pressure turbo is mounted further downstream in order to smooth out overall throttle delivery. Mercedes says the setup reduces turbo lag and helps broaden the torque curve across the rev range. Fuel pressure for the 2.1L’s direct fuel injection system is rated at 28400 lb per square inch, which according to Benz accomplishes the neat trick of delivering more power and lower exhaust emissions at the same time. Benz says the system’s high-pressure setup allows for the engine’s four piezo injectors to be adjusted even more precisely as engine load and speed change.
Treating the exhaust is Mercedes’ Bluetec Selective Catalytic Reduction System, which sprays a water-based urea mixture Mercedes calls AdBlue into the exhaust to help keep particulate matter in check and the E250 as clean as any E-Class from an emissions standpoint. AdBlue is refilled at 10000 mile intervals as part of the overall maintenance process.
At the press drive in Portland I first did a 70 mile, pseudo-hypermiling stint in a rear-drive E250, with only me in the car and the A/C on in mainly a 55mph zone, its stop-start mode killing the engine at every red light. I recorded 44.4mpg average on the instant mpg meter, far and away the best number of all the cars at the event. To be fair, most cars had two drivers and AWD (4Matic is a new addition to the E-Class diesel), but a win is a win. The best AWD car with two drivers turned in a tick north of 40mpg.
Any prospective E-Class buyer looking for everything but straight-line speed and at-the-limit handling would be well served to ...
The second leg of the trip was 170 miles or so, and hypermiling gave way to low-sulfur lead footing. While no one is going to confuse the E250 with the likes of the E63 AMG super sedan, the E diesel handled its business as I pushed it hard into the bends and elevation changes around Mt. Hood. Pop it into sport mode and with its capable seven-speed automatic pegged to the optimum gear (the paddle shifters were hit and miss and it was tricky to keep the car in the power band), the E250 proved relatively spirited, its suspension capable of keeping the car planted and in line through the mountain passes. Under hard acceleration or at idle, the engine still has that characteristic diesel note. Although never loud or overly intrusive, it’s maybe a smidge noisier than the outgoing six.
At the end of both loops the car’s instant mpg meter still touched almost 38mpg. Official EPA ratings for the 2014 E250 have just been announced, and it has crested the vaunted 40-plus highway number, extremely impressive for a car pushing some 4450 lb. The E250 has been rated at 28 city/45 highway for the rear-drive model and 26/42mpg for the 4Matic AWD car. The BMW 535d (26/37-38 mpg) and Audi A6 TDI (24/38 mpg) don't come close to the Mercedes-Benz E250 Bluetec in EPA-rated fuel economy, but those diesel midsize sedans also have more power and torque. The 535d gets a 255-hp 3.0-liter turbodiesel I-6 with 413 lb-ft while the A6 TDI's 3.0-liter turbodiesel V-6 produces 240 hp and 428 lb-ft.
As we’ve outlined previous E-Class drives, the 2014 E-Class isn’t a complete redesign, but the mid-cycle updates are significant. For the sedan, the sheet metal has been reworked, with sharpened, horizontal lines at the flanks. The sport model I tested (a luxury trim is also available) features a slick front-splitter look, and a massive, three-pointed star badge integrated into a thick, two-bar grille out front. Re-worked taillights and neatly integrated exhaust ports are the signature changes at the back. Inside, the instrument panel has been updated, as have many of the buttons and brightwork. As you’d expect, it’s quiet and isolated in the cabin. Despite the updates, the center stack and nav system are getting on in years and are the glaring areas in need of more love.
The E-Class is also the beneficiary of trickle-down tech and is available with a load of the latest safety nannies that have been rolling out across the Benz portfolio. Standard features include Benz’s collision prevention assist and attention assist. Optional tech and features include an around-view camera, full LED lighting, and a new driver assistance package highlighted by Benz’s Distronic Plus with Steering Assist. Distronic Plus is Benz’s adaptive cruise control that works amazingly well and Steering Assist does just what the name implies. It gently moves the steering wheel in lane and can actually steer itself for a short time. It’s wild and a bit spooky at the same time.
The E250 serves as the entry-level model, at $52325 for rear-drive and $54825 for the 4Matic, including destination. Depending on trim level it’s actually less expensive than the outgoing diesel. Any prospective E-Class buyer looking for everything but straight-line speed and at-the-limit handling would be well served to give the E250 a spin. While diesel may not ultimately be the future of propulsion, it’s certainly still in the mix at present, and the E250 is as green as an Oregon forest.
At least when it comes to its place in the E-Class lineup.
2013 Mercedes-Benz E250 Bluetec
Base price: $52325
Vehicle layout: Front-engine, RWD/AWD, 5-pass, 4-door sedan
Engine: 2.1L/195hp/369 lb-ft twin-turbo DOHC 16-valve I-4
Transmission: 7-speed automatic
Curb weight: 4450 lb (Motor Trend est.)
Length x Width x Height: 192.1 x 73.0 x 58.0in
0-60mph: 7sec (Motor Trend est.)
EPA city/hwy fuel econ: 28/45mpg (RWD); 26/42mpg (AWD)
Energy consumption, city/hwy: 137/85 kW-hrs/100 miles; 147/91 kW-hrs/100 miles
CO2 emissions: 0.66 lb/mile; 0.71 lb/mile
Availability: On sale in U.S. now