Take a glum Midwestern sky, add a hefty helping of fog and a generous glut of Chicago traffic seasoned with holiday shoppers, and you’ve got a pretty realistic setting to evaluate a small-displacement diesel engine designed for urban parcel and delivery applications.

The new engine is Detroit’s 5.1L, four-cylinder DD5, which the company launched earlier this year and has been available in Freightliner M2 106 vocational trucks since October. Detroit is primarily known as a builder of large-displacement, heavy-duty diesels, so the DD5 is something of a departure in many ways. At the same time, it is an indicator of things to come: Daimler Trucks North America, the parent company of Freightliner and Detroit, is committed to carving out a larger piece of  the urban delivery trucking market — a segment that continues to grow rapidly as e-commerce and the demand for ultra-fast delivery times increase.

According to Chris Moran, medium duty program manager of sales and marketing for Detroit, the DD5 is merely the company’s first step in filling out its diesel engine portfolio. A larger-displacement, 8L DD8 is slated to launch next year, which he said will give Detroit a powerful and fuel-efficient diesel to meet any need for fleets with vehicles from Class 4 up to Class 8.

The DD5 will serve Classes 5 and 6, Moran said, with two options: a 210-hp version generating 575 lbs-ft of torque, and a 230-hp unit with 660 lbs-ft of torque.

“Initially, we’re focusing on P&D, rental, lease and box- and service-truck applications,” Moran explained. “Our immediate plans are to get DD5 production up and running in Detroit by the fourth quarter of 2018 as well as launch the 8L engine.”

Daimler is a longtime player in the urban delivery market, although other manufacturers own a majority of the market – at least for now.

“When the decision was made to bring a small-displacement engine into North America, it was very important that we didn’t just show up with a ‘me too’ product,” Moran explains. “The DD5 debuted in Europe in 2013 and is a mature, proven product. So we knew it is a durable engine. But our testing shows that it is also 10% more fuel efficient than the leading engine in this class. We also can offer better maintenance intervals than our competitors, with oil and fuel filter changes every 45,000 miles, our Virtual Technician telematics system, as well as a B10 life of 450,000 miles.”

The DD5 is a four-cylinder engine – a design that has been traditionally suspect in the eyes of North American fleet owners from longevity and power points of view. But Moran said the engine’s parent-bore cylinder design has removed complexity from the engine, while a cast iron, deep-rib block has increased overall durability, and the engine’s overhead cam gives it plenty of low-end power to get a truck rolling and keep it both cruising and passing at highway speeds. “From an engineering standpoint, the DD5 has a lot of commonality with Detroit’s heavy-duty DD13 and DD15 engines,” Moran notes. “So we’re working from a proven formula that we know provides a solid foundation for power, performance and fuel efficiency.”

Crisp acceleration, brisk braking

Currently, the DD5 is offered only in the Freightliner M2 106 medium-duty truck. So an M2 configured as a box truck waited for us at the TransChicago Truck Group Freightliner dealership in Elmhurst, Illinois, for an evaluation drive.

Moran started by popping the M2’s hood and pulling it forward to reveal a neatly packaged four-cylinder diesel with a remarkably clean overall design. Wires, piping and all the usual component clutter have been skillfully minimized or relocated to create an engine with remarkable access to maintenance points and vital components. A technician can easily reach the top of the engine from ground level without a stepladder, and all key inspection points are both easy to eyeball and access.

Start-up was straightforward, and despite the cold Chicago morning, gauges showed the DD5 coming to life quickly and idling at normal operating temperatures inside of five minutes. The engine operation was remarkably smooth with no shudder or noticeable vibration. The engine is loudest at low rpms, with some “clatter” coming from under the hood, but overall, it’s a very quiet design, particularly at cruising speeds, when it can hardly be heard at all inside the cab.

Our test truck was equipped with an Allison 2500 Series automatic transmission, which gave crisp and instantaneous response when I accelerated out of the dealership into heavy Chicago traffic. In fact, had I not been briefed beforehand that the DD5 is a four-cylinder design, I doubt I would have guessed it, so brisk was the overall acceleration from a dead stop.

The initial stop-and-go traffic also gave Moran the opportunity to show me DD5’s extremely effective engine brake, which is activated by a dash-mounted flip-switch to the right of the steering wheel. The brake switch has three settings, Off, Low and High, which gave me an impressive amount of stopping power without putting my foot on the brake pedal. The engine brake engages immediately after you let off the accelerator pedal, and it is aggressive even at highway cruising speeds. Moran said Detroit is so confident in the design, it believes fleets running the DD5 will see increased brake life and a decrease in associated maintenance costs if drivers use the engine brake regularly.

Even with a fully loaded box, the DD5-equipped M2 showed consistently crisp throttle response and brisk acceleration as I worked my way through a long series of traffic lights heading toward the entrance ramp to I-290 West toward the Chicago suburbs. I really put my foot into it as we took off down the freeway entrance ramp, and was impressed to see that the M2 was already going 55 mph by the time I needed to merge into traffic. Once I was at cruising speed, I had to be mindful of the speedometer, as the DD5 had no trouble quietly and quickly moving past the posted 55 mph speed limit. Traffic flow on I-290 was about 65 mph, which the DD5 had no problem maintaining. A bit later on, in a passing situation, the engine quickly got the M2 up past 75 mph, with the engine brake, in High setting, quickly decelerating the vehicle once I was past the offending car.

Overall, the engine performed admirably, with impressive acceleration and cruising characteristics. Interior noise levels are low throughout the engine’s power curve, and the Detroit engineers deserve a special tip of the hat for the engine’s integrated engine brake and its extremely effective performance.

The Freightliner M2 is well-known for its excellent handling, vision and turning radius. Already a highly effective urban delivery truck, it’s safe to say that the addition of the DD5 will only complement the M2 package and give fuel- and maintenance-focused fleets a potent delivery truck capable of working effectively in a variety of delivery roles.

The addition of Daimler’s Virtual Technician telematics system takes the overall package to another level, with Moran noting that medium-duty DD5 customers will be able to leverage the same access to repair information, dealer bay access and expedited diagnosis and repair times that the company’s heavy-duty customers do.

Far from a “me too” product, Detroit has delivered a fuel-efficient four-cylinder diesel that can work as hard as any medium-duty diesel on the market today.

Jack Roberts holds a commercial driver’s license and does Test Drives on all classes of trucks. In addition, he specializes in equipment and advanced technologies and writes the Truck Tech blog on Truckinginfo.com.