Inside Freightliner's SuperTruck

If a fleet operator reported that its average fuel cost was in the order of $142.95 per litre ($US418 per US gallon), you'd be inclined to think there could be some major savings due. Well, in December 2011, that’s exactly what the US military reported as the cost of battlefield delivery of fuel to its enormous fleet of vehicles. The cost included security, storage, transport and dispensing equipment – in other words, the whole associated infrastructure.

But today's world demands efficiencies from every corner of expenditure, so the US Army funded a Small Business Innovative Research program to identify advanced diesel technologies. The goal was 42 per cent brake thermal efficiency which, in the most basic terms, is a measure of how much heat in a fuel is translated to work.

Then the US Department of Energy (DoE) partnered with major manufacturers to look at similar possibilities in heavy trucks, mainly because as this sector carts around 80 per cent of all goods used by Americans, it accounts for nearly 20 per cent of diesel fuel consumption.

The goal was to develop a prime mover and single trailer that would improve the freight hauling efficiency of this class (known as Class 8 in the US) by 50 per cent. The program was branded SuperTruck, and DoE offered dollar-for-dollar funding to those manufacturers who stepped up. Daimler’s Freightliner boffins went to work, and eventually achieved a staggering 115 per cent improvement in freight efficiency...

I recently drove in the truck that posted the record and carefully watched all the indicators that illustrated the energy saving features of this amazing vehicle. A tablet display illustrated the three main storage systems – the fuel tank, the battery pack, and the hydraulic accumulator – and how power was introduced and used.

For example, the battery pack is fed power from several systems. Solar panels on the trailer roof were generating 2.4kW/h during my drive. Braking energy recovery, which is no longer unique, was engaged and fed electrons to the battery through the hybrid motor. The truck's 'Accusteer' steering system generates and then directs hydraulic pressure into a reservoir for the steering and engine cooling fan, reducing parasitic losses. An on-board boiler system extracts exhaust heat to boil ethanol (which bubbles at 70 degrees C) – this then drives a generator through a turbine for additional battery power.

The battery itself shares its power between the drive system, the air-conditioning system, and a 12-volt system for cab lighting and other gadgets.

Packaged together, they enable an 11-litre engine to be used instead of a 13-litre one, and the engine management software is mapped to keep engine revs at a minimum. In its latest test, it ran at just under 30 tonnes at an average speed of 65mph (105kmh), achieving an average result of 12.2mpg (4.4km/lt).

And that’s not just from the engineering. On the outside, ultra-aerodynamics shroud the truck and trailer from tip to tail. The entire rig is shod with low-rolling-resistance tyres, while the engine grille will adjust from wide open to completely shut to maintain the most efficient engine temperature.

Although some systems on the SuperTruck were deemed to be at least 10 years away from the market, Freightliner has thrown everything it has at this concept to establish a benchmark of possibility. It's now up to the evolution of infrastructure and regulations to see these remarkably efficient machines on our roads sooner rather than later…