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Daimler Trucks NA SuperTruck achieves 115% freight efficiency improvement over 2009 baseline; 50.2% engine BTE

DTNA’s SuperTruck was unveiled at the 2015 Mid-America Trucking Show. Click to enlarge.

Daimler Trucks North America’s (DTNA) SuperTruck program has achieved 115% freight efficiency improvement (gallons of fuel consumed per ton of goods moved per mile traveled)—surpassing the Department of Energy (DOE) program’s goal of 50% improvement and exhibiting the best results of all reporting OEMs. (Earlier post.) DTNA unveiled its SuperTruck at the 2015 Mid-America Trucking Show (MATS) in the Freightliner Trucks booth.

To measure freight efficiency, DTNA ran vehicle testing on highway routes in Oregon and Texas; one city route in Portland, Ore.; and anti-idle testing in both a cold chamber and hot chamber. These tests resulted in the combined 115% freight efficiency improvement over a 2009 baseline truck. Testing was also conducted at the DTNA Detroit engineering facility to demonstrate engine efficiency by achieving 50.2% engine brake thermal efficiency.

The final SuperTruck demonstrator ran a five-day, 312-mile (502-kilometer) roundtrip route on Texas Interstate 35 between San Antonio and Dallas, at a weight of 65,000 lbs (29,484 kg) GVWR at a speed of 65 mph (105 km/h), where it achieved an average result of 12.2 mpg (19.26 l/100 km).

We are thrilled with the positive results, and are honored to have been part of the program. It is our expectation that we will continue to review and refine what we’ve learned and achieved over the course of the SuperTruck initiative, and use that knowledge to bolster our leadership in fuel efficiency.

—Derek Rotz, principal investigator for SuperTruck, Daimler Trucks North America

DTNA SuperTruck technology elements. Click to enlarge.

Powertrain. The Freightliner SuperTruck uses a downsized and downsped 10.7-liter engine, a hybrid system, a Waste Heat Recovery (WHR) system, along with a number of other upgrades.

  • The 390 hp/1400 lb-ft torque (291 kW/1,898 N·m) engine features 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.

  • Friction-reducing measures include 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.

  • 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.

  • Working in conjunction with Daimler Advanced Engineering, the team developed an innovative organic Rankine cycle (ORC) waste heat recovery (WHR) system that converts a portion of the exhaust heat into usable energy.

    The aftertreatment system features additional insulation to retain maximum heat energy in the exhaust. These exhaust gases pass through a boiler which transfers heat to the working fluid, which vaporizes to high-temperature steam and builds up pressure. High-temperature, high-pressure steam then passes through an expansion machine, which recovers the usable energy.

    After expansion, the medium-temperature, low-pressure steam circulates to the condenser, where it liquefies. The liquid is then pumped back into the boiler to recover more heat.

    DTNA notes 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.

  • A hydraulic fan eliminates frictional losses generated even when the fan is off by belts, pulley, bearing and seals and spins the fan at precisely the speed needed to cool the engine.

  • 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.

  • 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.

  • The SuperTruck’s AC system runs entirely off the electricity powered by the hybrid system. Drivers can run the AC for more than an hour without turning the engine on, resulting in significant reductions in fuel consumption.

  • 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.

Phase 2 standards for medium- and heavy-duty GHG emission standards
Staffs of the US Environmental Protection Agency (EPA), National Highway Traffic Safety Administration (NHTSA), and California Air Resources Board (ARB) are working on the next phase of greenhouse gas emission standards for medium- and heavy-duty vehicles, referred to as Phase 2.
These standards are expected to build on the improvements in engine and vehicle efficiency required by the Phase 1 greenhouse gas emission standards, and provide an opportunity to achieve further greenhouse gas reductions for 2018 and later model-year heavy-duty vehicles, including trailers.
US EPA and NHTSA are planning to issue a Notice of Proposed Rulemaking for the Phase 2 standards in the spring of 2015 and a final rule in the spring of 2016. Upon federal adoption of the Phase 2 standards, ARB staff plans to present a proposed California Phase 2 program to the Board, most likely in late 2016 or 2017.

Chassis. The truck chassis was redesigned as well. The frame rails uses fewer crossmembers, thereby delivering added weight savings, simplified crossmember construction and better use of lighter-weight materials. This, combined with the lightweight rear suspension, reduces frame weight by 700 pounds (318 kg).

The AccuSteer power steering and air system with a hydraulic accumulator reduce overall energy consumption by more than 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 more than 90% of the time.

Detroit rear axles were 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.

Aerodynamics. The basic shape originated as a 3D computer model, which was carefully honed by aerodynamicists using digital wind. Together, the optimized tractor and trailer design achieved a 54% reduction in aerodynamic drag.

  • The 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.

  • An active grille stays open in low-speed, high-torque situations to maximize cooling flow. At highway speeds, it automatically closes, improving aerodynamic efficiency.

  • The windshield is raked backward to guide air more efficiently over the hood and cab, moving over the truck with less drag.

  • Optimized side extenders shield cab components as air glides from tractor to trailer.

  • The SuperTruck’s wheel fairings divert air past the rear wheels and tires, and articulate for easy serviceability.

Several commercially viable technologies developed in conjunction with the SuperTruck program have been introduced in DTNA production vehicles, including 6x2 optimization and the aerodynamic components found on the Freightliner Cascadia Evolution and the integrated Detroit Powertrain. Other components, due to regulatory or economic barriers, may not be commercially viable in the near future.

By incorporating a mix of available technologies with future innovations, we were able to use the SuperTruck program to take the first steps in seeing what may be technically possible and commercially viable. We still have a long road ahead to determine ultimately what will be successful and what will achieve the greatest efficiencies.

—Derek Rotz

Sponsored by the US Department of Energy (DOE), the SuperTruck program was a five-year research and development initiative to improve freight efficiency by at least 50%, brake thermal efficiency by 50%, and reduce fuel consumption and greenhouse gas emissions of Class 8 trucks. DTNA and three other major truck OEMs were awarded multi-million dollar grants by the DOE and each matched the DOE funding dollar for dollar.

SuperTruck is supported by the US DOE under the American Recovery and Reinvestment Act of 2009. DTNA began work on the SuperTruck program in 2010 together with Detroit and other partners, including national labs, universities and suppliers. Partners included:

  • Aftertreatment: Corning, Eberspacher, Johnson Matthey.

  • Aero/cooling: Auto Research Center, CD-adapco, Freight Wing, Lang Mekra, Modine, TitanX, Truck-Lite.

  • Engine: Air Squared, Aradex, Atkinson LLC, Bowman, Daimler, Gigatronik, Massachusetts Institute of Technology, Oak Ridge National Laboratory, Obrist.

  • Powertrain: Accuride, Ashland, Bendix, ConMet, Detroit, Michelin, Parker, Sheppard.

  • Hybrid: A123 Systems, Eaton, FUSO, ITK Engineering, Mercedes-Benz, MiaSole, US Hybrid.

  • Energy Management: Delphi, Denso, Grakon, Guardian, National Renewable Energy Laboratory, Oregon State University, Telogis, US Department of Energy.

  • Fleet: Schneider, Walmart

  • Lightweighting: MSI-ACPT, Maxion Inmagusa, Oregon State University, Strick, Toray.




".. San Antonio and Dallas, at a weight of 65,000 lbs (29,484 kg) GVWR at a speed of 65 mph (105 km/h), where it achieved an average result of 12.2 mpg (19.26 l/100 km)."

".. achieves 115% freight efficiency improvement over 2009 baseline;"

Curious how much efficiency improves after an "addicted to oil" war criminal is replaced.


"Freight efficiency" assumes a full load. Not a bad way to measure efficiency in freight transport to be sure, but you still have to keep that in mind.

Also 12.2 mpg is pretty darn close to the 13.4 mpg achieved by this company;


I wonder how all that aero will hold up... I mean the roads are not friendly, snow and other obstacles may keep these trucks from traveling in certain conditions.

Yes, if tires were replaced before they blew out this would probably be okay.

Roger Pham

Great Accomplishment, Daimler-Benz! All the fuel-efficiency tricks known in the books are being used in this Super Trucks, so it looks like this will be it, for maximum turbodiesel semi-truck efficiency. The next step has got to consider Hydrogen Fuel Cell to raise efficiency another notch!

Hydrogen FC would definitely be practical in semi-trucks in order to build a distributed demands for excess wind and solar electricity in the Great Plains. Wind and solar electricity at many locations in the Great Plains can be a stranded asset due to long distances to major cities, requiring expensive power lines that will add significantly to the final cost of wind and solar energy. In addition, backup NG power plants must be on standby for backup in calm days, thus adding to investment cost and maintenance cost. When excess RE power is used to produce H2, the energy cost of H2 production will be low, and can be cost-competitive with ultra-low-sulfur diesel fuel in consideration of the higher efficiency of the FC.

Ultra-low sulfur diesel fuel is not cheap to produce, and ultra-low-emission large diesel engines are expensive to produce. Fuel cells and electric motors can be modular and hence lower in cost when the private FCEV market will be sufficiently large to permit mass production, when automotive FC and motors and power controllers can be lifted right off the automotive market to be put on large trucks. Truck engines and most components are one-off design specialized for each task in order to optimize energy efficiency, strict emission regulation, and durability, hence will remain expensive, in comparison to modular-design FC, motor and controller produced in mass quantities for any kind of vehicles, no matter what size, shape, etc.

Weight-wise, a H2-FC propulsion system including fuel, would be much lighter.
A 400-hp turbodiesel engine weighs about 2,600 lbs, plus requiring 60 gallons of fuel for 720-mi range at 12 mpg, weighing 500 lbs with the tanks, and a 12-16-speed transmission weighing ~600 lbs, for a total of 3,700 lbs.
A 300-kW fuel cell and motor at 2 kW per kg for FC and motor + controller would weigh 300 kg (660 lbs), plus 50 kg of H2 using CF tanks at 6% weight % would weigh 833 kg (1,833 lbs), plus a 3-4-speed transmission weighing ~150 lbs would have a total weight of:
660 + 1,833 + 150 = 2643 lbs.

Thus, the H2-FC version with full fuel for 720 miles would be over 1000-lb lighter than a comparable turbodiesel version.
720-mile distance is 11 hrs at constant speed of 65 mph! Federal law now restricts truck drivers to only 8 hrs driving shift!


a: well done

b: You would want to look at the costings for each improvement and then start to bring the less expensive ones (/ mpg increase) into real world trucks.

c: IMO, the best way to distribute excess electricity from wind/solar would be to build (HVDC ?) lines to distribute it across the country. This won't be cheap, but you can't store electricity (economically), it is better to push it elsewhere and sell it.

Roger Pham

>>>>" This {HVDC lines] won't be cheap, but you can't store electricity (economically), it is better to push it elsewhere and sell it."

Spending a lot of money to build HVDC lines while continue to import oil instead of making H2 for transportation?


earlier.. "Also 12.2 mpg is pretty darn close to the 13.4 mpg achieved by this company;"

After all the cheering is over, can over 30 tons actually be hauled around on US roads/hills at US highway speeds?

Aren't there some pickups around getting getting under 12 mpg?


h2 is a lousy fuel. You have enormous loses generating it and storing it. It is crazy to use excess electricity to make H2, better to send it elsewhere.

DOes the US import much oil - I am not so sure any more. If you want to use natural fuels (work on natural gas powered trucks and vehicles - [a much better fuel IMO]) and hybridisation and EVs. Long distance trucks and aviation seem to me like the last things that should move off chemical fuels.

You can electrify trains and short range vehicles with wires and batteries, but long range trucks and aviation are beyond this.
(Maybe you could build an electric truck highway, but it would be hard to do and expensive).

Maybe you could have self driving trucks where the driver could sleep for some of the time. Then the trucks could go at 55mph and save a load of fuel.


With future autonomous drive e-vehicles, a high safety, higher speed electrified (left) lane could become a possibility.

Not so sure that heavy e-truck could match the correct speed unles they are equipped with a high speed kit.

Accepted e-vehicles should be able to do a steady 110 to 130 kph and follow the road speed indications while keeping a safe minimum separation between vehicles. Passengers could rest, workd or play games between pre-planed stops.


The Citroen C4 Cactus Airflow 2L achieved 141 mpg or 2.0L/100Km using improved air flow design and lighter bodies and more efficient diesel engines. Their DS-5 wagon is also using some of the techniques developed for the C4.

The same improved air flow techniques and light weight bodies apply to trucks, vans, pick-ups to get improved mileage.

Roger Pham

>>>>"h2 is a lousy fuel. You have enormous loses generating it and storing it."

Truckers don't much care about losses in H2 generation and storage. If H2-FC-powered semi-trucks will be less expensive, just as convenient, and more comfortable, they will use it.
When the H2 fuel will be made from surplus wind and solar electricity, it will be cheaper than petroleum on per-mile basis.

For example, surplus solar and wind power will eventually go for as low as 2 cents per kwh. It takes 53 kWh to make 1 kg of H2 at 10,000 psi, so the energy cost will be $1.06 per kg, adding to that $0.57 cost to make that 1 kg of H2, so:
$1.06 + $0.57 = $1.63 cost to make 1 kg of H2. Adding profit and taxes and it can be sold at $3 per kg, which is the same as 1 gallon of diesel fuel, but can travel about 15-20% further due to higher efficiency of FC. Plus, it will cost less to purchase a FC-H2 powered tractor than a diesel one for reasons already mentioned.
Which do you think truckers will ultimately choose?

>>>>"It is crazy to use excess electricity to make H2, better to send it elsewhere."

It would be more crazy to waste those "excess" electricity by not making H2, because when it is determined to be "excess", it has no where to go!


We have both hit on the main problem of large scale renewable electricity production - what to do with the excess.
You say turn it to H2, I say export it to someone who can pay wholesale rates for it.
Both approaches are valid in some mix.

Another problem is what to do with night time electricity when you can't really export it as everyone has night at the same time within about 5000 miles.

THEN, you may need something new to do with it: (Make Ice for AC, make H2, pump it up a hill, make anything that stores the energy).

This is one of the problems of the age (and not a simple one).

an aside - interesting to see that coal usage has stalled in China - maybe too many important people's grandchildren died or got sick.

Thomas Pedersen

a: low-cost excess renewable electricity (RE) will be used with heavy subsidies from electricity consumers. Wonder how they feel about sponsoring trucking fuel?

b: the capital cost of electricity-to-HP-H2 systems virtually negates the option of only running them at times of excess RE.

c: In all but very stable climates, the challenge of storing and using intermittent RE is not one of hours - which can often be absorbed by the grid quite easily - or even days, but weeks, months, seasons and even years. Year-by-year wind energy potential can vary by as much as 30% or more. But once you have established consumers for HP-H2, they need that product regardless of whether the wind blows or not.

The 12 mpg equates to quite close to 1.0 kWh/km (1.6 kWh/mile) at 50.2% thermal efficiency. Probably less, considering average efficiency. How many Tesla-batteries would be required to drive as far as a driver is able/allowed to between stops? 10-15?

Battery swapping - which did not work out too well for Better Place - is the ultimate technology for absorbing 'excess' RE for transport. Another conceivable option would be for trucks to preferentially stop for re-charging when power is cheap. Assuming that there is anything to gain from it, and regulations 'reward' a two-hour break with additional allowed driving time.

It is a common misconception that trucks and (passenger) trains cannot use batteries. Quite often, the payload/volume penalty of having batteries in a car with sufficient range is much higher than for heavy vehicles such as trucks, trains and ferries. The same goes for drive train costs. A recent study in Denmark concluded that short-haul ferries can benefit from battery operation to much greater extent than cars.

Furthermore, fast-charging infrastructure is more feasible for fewer, heavy use professional vehicles. In particular trains and ferries that are tied to a few certain physical locations in their operation.

Many used to have an "OMG, it can't be done!" attitude to high-power charging. But now Tesla is doing it routinely, with no problems. Busbaar charges with even higher power. The limit is really only set by the charge acceptance of the batteries. Trains go from zero to several MW power usage in a matter of just a few seconds. The electric infrastructure to deal with all of this has been invented long ago. We just need to connect the dots and figure out that if amortization of power train + fuel works for Tesla, then it could likely work for many truck applications as well.

And if it make the owner/driver feel better, install small 50 hp diesel genny as limp-home backup.

Oh, and BTW, great job on improving the truck!! 115% efficiency improvement is something to consider for the politicians. The added cost, whether positive or negative, to consumers of implementing these measures could hardly be felt. Pennies per month.


Here's an idea: Electrify the highways, either through induction coils in the road or overhead cables; put use enough batteries as are needed for travel on the non-electrified roads between them.

Roger Pham

@Thomas Pedersen,

a: Subsidizing RE to make H2 would still greatly benefit the environment, help reduce oil importation, and should be welcomed by the taxpayers.

b: Solar and wind can complement each other to keep electrolyzers employed more often. Electrolyzers will soon be made of non-precious metals which will be a lot cheaper.

c: H2 can be stored in vast underground reservoirs used to store NG before, in vast amount that can span many seasons, at very low cost.

1 gallon of diesel fuel has ~38 kWh of thermal energy. At 50% efficiency, 19 kWh is available to propel the vehicle. So, 19 kWh for 12.2 miles = 1.56 kWh per mile. Therefore to travel 500 miles between truck refueling stops, one would need 500 x 1.56 / 0.80 elec. eff = 973 kWh. The Tesla MS battery pack weighs 1300 lbs for 85 kWh, so, 1,300 / 85 x 973 = 14,881 lbs. Just imagine substracting 13,000 lbs from the payload capacity of a turbo-diesel semi-truck when using batteries! I don't think the tractor cab part can handle that much added weight of the batteries.

However, an H2-FC version of semi-truck with 300 kW of power and 720 mile-range would weigh 1000-1,500 lbs LESS than the turbo-diesel version. Look out for many H2-FC semitrailer trucks in the future!

Roger Pham

Continued from above:

Furthermore, Thomas, Battery swapping of that much battery capacity would be a very expensive investment due to the sheer number of batteries needed in stock. For fast 1-hour charging to 100% or half hour to 50% of battery capacity of each 973-kWh pack, 1 MegaWatt of electric power will be needed PER PACK in the MiddleofNowhere, USA. You will need either fast charge capability or else your number of battery packs in slow charging will be very high and investment costs very high, and the power to charge all these packs in slow charge will be the same as fast charging much fewer packs.

Have you ever been to a truck re-fueling stops, where there could be a bunch of trucks refuel at any given time, in much less time? Just getting the power there alone ain't cheap. How on earth do you suppose intermittent solar and wind energy can supply the power for multi-MegaWatt Super-Truck charging? Without wasting much of the RE in sunny and windy days with fewer charging trucks, while depending on fossil-fuel energy in calm and rainy days where there won't be any RE available? What about the additional costs of capital investment and maintaining backup fossil-fuel power plants for rainy and calm days? What would that do to the overall prices of RE backed-up by fossil-fuel power plants?

With Hydrogen refueling, there will need be a piping system transporting H2 from a central depot supplied by a bunch of local electrolyzers fed with solar and wind electricity, but that's it. No need for backup fossil fuel power plants due to the capability of vast hydrogen storage.


Long range Heavy e-trucks may not be practical until 10X batteries become available at a reasonable price.

Recharging (many) 973 kWh battery pack quickly may be a challenge for many current chargers and electric distribution networks.

Alternatively, such very large battery packs may be temporary split into 3 or 4 packs to reduce the size of chargers and cables.

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