Freightliner SuperTruck freight efficiency improvement, surpassing the SuperTruck Challenge's 50% freight-efficiency goal.
Miles the SuperTruck can travel on a gallon of diesel fuel. Most trucks today average half that.
CPU hours required to build the SuperTruck.
A Global Team
In low-speed, high-torque situations, the grille stays open to maximize cooling flow. At highway speeds, it automatically closes, improving aerodynamic efficiency.
The SuperTruck's overall ride height can be adjusted, raising the chassis for extra ground clearance at low speed for maneuverability and lowering it at highway speeds to reduce drag.
The windshield is raked backward to guide air more efficiently over the hood and cab, moving over the truck with less drag.
Meet the most aerodynamic mirrors allowed by the U.S. Department of Transportation. The SuperTruck's main mirrors are as aerodynamic as the truck itself, their shape carefully crafted by – and tested in – digital and real-world wind tunnels.
Optimized side extenders shield cab components as air seamlessly glides from tractor to trailer.
Tires are infamous for creating turbulent air. The SuperTruck's fairings divert air past the rear wheels and tires, and articulate for easy serviceability.
Traditionally, trucks are conceived by designers who sketch them out on paper, with an eye toward form. The Freightliner SuperTruck took an unconventional approach. The basic shape was born as a 3D computer model, which was carefully honed by aerodynamicists using digital wind. After six months of analysis and countless computer simulations, the Freightliner SuperTruck took shape, every curve and surface optimized to reduce drag and boost efficiency.
A Tale of Two Shapes
Less is more. Like the other systems built into the Freightliner SuperTruck, Freightliner engineers put the frame through numerous simulations to find the perfect ratio of strength and weight savings. The result? Fewer crossmembers for added weight savings, simplified crossmember construction and better use of lighter-weight materials, which thrive in harsh environments where trucks operate. This combined with the lightweight rear suspension reduces frame weight by 700 pounds.
The highly efficient Detroit DT12™ Automated Manual Transmission is even more efficient on the Freightliner SuperTruck. Its Direct Drive and eCoast technologies work in tandem with the SuperTruck's Predictive Technologies to improve shifting based on vehicle speed, engine torque and upcoming road grade.
Detroit™ rear axles have been upgraded for the Freightliner SuperTruck. In addition to using lighter-weight components where possible, the axle configuration, oil level management system and even the oil formulation itself are optimized to reduce friction and increase efficiency.
The Freightliner SuperTruck's wheels have evolved in numerous ways to reduce rolling resistance. For one, engineers redesigned the hub and wheel with lightweight materials. Additionally, Daimler engineers collaborated with Michelin to create specially formulated tires with an exclusive compound to further reduce rolling resistance.
The AccuSteer power steering and air system with a hydraulic accumulator reduce overall energy consumption by over 1%. On standard systems, the air compressor and power steering pump run continuously, whether they're needed or not. The SuperTruck incorporates a clutch to switch these "parasitic loads" off when not needed, which, according to testing, is over 90% of the time.
The engine fan in most highway tractors is turned off the vast majority of the time. That's pretty efficient. Why bother looking into improving it? Turns out that while the fan is off, the belts, pulley, bearing and seals still produce friction. The Freightliner SuperTruck's hydraulic fan eliminates these frictional losses and spins the fan at precisely the speed needed to cool the engine.
At first glance, the Freightliner SuperTruck's chassis may look like an ordinary chassis. But that's where the similarities end. In addition to the all-new powertrain, cab and exterior, the chassis was redesigned from the ground up as well.
Pounds lighter than a standard tractor frame.
Fewer parts needed to build SuperTruck crossmembers.
Pounds saved with new rail reinforcement strips.
Detroit's engineers performed exhaustive simulation studies to determine the ideal powertrain to achieve the highest possible freight-efficiency gains. Based on these results, they opted for an approach focused on downsizing and downspeeding to reduce weight and friction throughout the engine. The right balance of size and efficiency was struck in the form of a downsized 11-liter engine rated at 390-hp/1400 lb-ft torque.
Working in conjunction with Daimler Advanced Engineering, an innovative system was developed that converts a portion of the exhaust heat into usable energy.
All trucks today utilize urea-based SCR systems to reduce smog-forming NOx emissions. The Freightliner SuperTruck features a low-back-pressure, next-generation aftertreatment system that efficiently removes NOx from the exhaust stream. This ensures the air coming out the tailpipe stays clean, while freeing up the engine to run more efficiently at higher temperatures and pressures.
The Freightliner SuperTruck's prototype 11-liter engine features efficiency-boosting innovations, including a revamped combustion system. To achieve the highest efficiency possible, engineers increased the compression ratio, ran extensive tests on piston and injector combinations, and pushed each engine component to its limit.
Designed specifically for high efficiency, the turbocharger provides just the right amount of air for efficient operation, while minimizing any restrictions or losses in the air system.
The SuperTruck engine features many friction-reducing innovations, including a variable speed water pump, a clutched air compressor, low-viscosity oil and an improved cylinder kit. To further reduce friction, the cylinder liners were optimized to reduce drag in the mid-stroke, where piston speeds are highest.
The SuperTruck uses a unique prototype control system, capable of optimizing engine performance in real time for maximum fuel efficiency. The controller continuously monitors the engine's operating conditions as well as the external environment, and uses an on-board computer to determine the most efficient course of action during real-world operation.
Part of the SuperTruck Challenge pushed manufacturers to create an engine that delivers 50% brake thermal efficiency. The Freightliner SuperTruck engine hit the mark, in the form of a downsized and downsped 10.7-liter engine, a hybrid system, a Waste Heat Recovery (WHR) system, along with a host of other upgrades. From top to bottom, the Freightliner SuperTruck is an extreme example of what can be done in the pursuit of peak efficiency.
The Freightliner SuperTruck's many innovations are efficient in their own right. But with innovative energy management-optimized hardware and software, the entire truck becomes more efficient, not just in simulations or wind tunnels, but in the real world, too.
Like the rest of the truck, no detail was left behind in the cab's development. Engineers and designers examined lightweight materials, design and manufacturing methods. They brainstormed on several interior concepts and spent countless hours looking for ways to make the interior as lightweight and efficient as the exterior.
The SuperTruck's sleeper cab is a showcase of lightweight materials. From the carbon fiber cabinets to the innovative mattress construction and every surface in between, all the materials have been carefully selected to minimize weight and maximize efficiency.
Throughout the gleaming white sleeper are flashes of yellow. These points indicate functionality to help the driver become more efficient whether they're behind the wheel or in the cab.
While it minimizes weight, the SuperTruck's cab also maximizes space. The bunk folds up to reveal a desk with three seats. The passenger chair swivels 180 degrees so drivers and passengers can work, live and drive comfortably, whether parked or on the road.
The SuperTruck's cab should look and feel every bit as futuristic as it performs. Virtually all electronic systems – from recessed LEDs that can display millions of colors to a hidden entertainment system – are controlled via multiple touch-screen tablets located throughout the cab.
In 2009, the U.S. Department of Energy challenged truck manufacturers to push the envelope on experimental high-risk, high-reward technologies to develop and demonstrate a highly efficient truck that's at least 50% more freight efficient. As if that wasn't daunting enough, the SuperTruck Challenge also demanded the engine show at least 50% brake thermal efficiency. No easy feat.
So how do you make a 12.2 MPG, 115% freight-efficient Freightliner SuperTruck? Along with countless innovations – some of which may not be production viable anytime soon – you call in hundreds of the best and brightest engineers you know.
The Freightliner SuperTruck is a showcase of innovation and efficiency. It's also a prime example of what is possible when experts across Daimler, universities, national labs and partners unite with a common cause. The SuperTruck program was divided into eight workstreams, each with its own efficiency goal: aerodynamics, engine, powertrain integration, parasitic losses, hybrid, lightweighting, energy management and waste heat recovery.
Each team started with a clean slate. Nothing was off limits, and no stone was left unturned as they uncovered ways to make the Freightliner SuperTruck lighter, more aerodynamic and more efficient. From developing unconventional shapes to maximize aerodynamics to testing various rubber compounds to create low-resistance tires and every millimeter in between, SuperTruck engineers were relentless in their quest for greater freight efficiency.
The SuperTruck Challenge asked, "How far can you push technology without constraints?" Freightliner engineers responded with the Freightliner SuperTruck.
In an effort to meet the Challenge's 50% goal while also keeping an eye toward customers' payback time and lowering their Real Cost of OwnershipSM, engineers explored experimental high-risk, high-reward technologies as well as near-term technologies to make the truck lighter, stronger and more efficient.
Core development of the Freightliner SuperTruck and engine was accomplished at Daimler Trucks North America and Detroit. However, it takes a village to build a truck. Over the course of its five-year development, engineers throughout the global Daimler organization were tapped for their expertise, and leveraged the knowledge base of the most prestigious universities and national labs across the United States.
The SuperTruck Challenge presented a unique opportunity. For the first time, Freightliner engineers were tasked to make not just the tractor more efficient, but the trailer as well. Aerodynamicists always had a hunch that optimizing the tractor and trailer is best done together as one complete system. The SuperTruck provided the chance to prove them right.
Testing revealed significant drag occurring underneath and behind the trailer. Side skirts were added beneath the trailer to channel air past the rear wheels, while adjustable tail fins guide air to fill the void behind the trailer. The results were astonishing: together, the optimized tractor and trailer design achieved an incredible 54% reduction in aerodynamic drag.
The Freightliner SuperTruck is as aerodynamically efficient as a truck can get. We know this because the team evaluated countless shape combinations both computationally and in the full-scale wind tunnel until settling on two. One of those early shapes formed the basis of the SuperTruck as it appears today. Internally named "Notional 3," this shape accommodated a beefed-up cooling package within a large hood in a fenderless aerodynamic form.
The other concept was called "Notional 1," with an aggressively reduced hood and a smaller grille. To meet cooling demands, the cooling package in Notional 1 was mounted mid-chassis with a roof scoop to direct airflow. While Notional 1's unconventional shape offered better thermodynamics under full engine load, Notional 3 offered advantages in aerodynamics, chassis real estate and cab functionality.
Once a shape was chosen, the real testing began. Freightliner engineers continued to refine Notional 3's shape in scale model testing to squeeze every bit of aerodynamic advantage out of it.
The Freightliner SuperTruck features an innovative Waste Heat Recovery (WHR) system powered by Detroit that converts the engine's otherwise wasted exhaust heat into usable energy. However, waste heat recovery systems have several technological challenges that remain to be resolved before they become commercially viable. Watch the video above to see it in action.
When you set out to make a highly efficient engine, it helps to start with a highly efficient heavy-duty engine platform. Powering the Freightliner SuperTruck is a prototype 10.7-liter engine, sized to match an efficient vehicle and optimized to work with the truck's hybrid and Waste Heat Recovery systems.
Significant enhancements were made to the SuperTruck engine's combustion design, turbocharger, piston kit and control system to squeeze out every last bit of performance and efficiency to meet the daunting goal of 50% brake thermal efficiency. The smaller engine contributes to the truck's overall freight efficiency goal, and the torque curve and fuel map have been specifically optimized for downsped powertrain operation. In the end, the SuperTruck engine exceeded the target by measuring 50.2% brake thermal efficiency.
Note that while Waste Heat Recovery is an innovative SuperTruck technology, challenges remain in the areas of vehicle and engine integration tradeoffs, working fluids, and cost and maturity.
The Freightliner SuperTruck isn't just a reflection of what lies ahead, it knows what lies ahead. Using GPS and 3D digital maps, the Integrated Powertrain Management System controls the SuperTruck's vehicle speed, shifting and eCoast. The SuperTruck also incorporates Predictive Hybrid Control, which optimizes hybrid battery-charging strategies to the terrain of the road ahead.
Solar panels run the length of the top of the SuperTruck's trailer, helping to charge the hybrid battery, which in turn powers the eHVAC system. On a sunny day, the panels can provide enough energy to run the AC system continuously without the engine running.
The SuperTruck's hybrid system takes kinetic energy generated from downhill braking to charge its battery. Making the system even more efficient, eCoast technology senses downgrades or when the truck is about to crest a hill, and automatically shifts the drivetrain into neutral. This reduces friction, and increases efficiency and fuel economy.
Normal trucks' HVAC systems run off of energy created by the engine. That means a 455-hp engine is using expensive fuel to run a 2-hp compressor. Surely we can do better. And we did. The SuperTruck's AC system runs entirely off the electricity powered by the hybrid system. So drivers can run the AC for over an hour without turning the engine on, resulting in significant reductions in fuel consumption.