STUTTGART, Germany -- Over a seven-day, 7,900-mile run completed at the Nardo motor-race circuit in Southern Italy, a state-of-the-art Mercedes-Benz Actros cab-over tractor with a dry-van trailer posted a spectacular 12.10 mpg.

The latest generation 40-tonne Actros pulled a 55,000-lb payload, giving the 88,000-pound GCW combination an economy payload factor of 0.000001503 gal-per-pound of freight hauled per mile. In European terms this is expressed as liters/tonne/km. The Actros scored 0.78 l/tkm.

From an environmental perspective, the Actros reduced CO2 emissions to 20.5 grams per tonne of payload kilometre (g/tkm). By comparison, an 1,800-lb car running at 29 mpg would produce 53 g/tkm of CO2.

According to Daimler, state-of-the-art Mercedes-Benz technology underpins the record-breaking results. The conventional commercial vehicle diesel engine featured the new BlueTec selective catalytic reduction emissions technology that has demonstrated two to five percent lower fuel consumption. An enhanced drive system promises additional potential savings with the standard Mercedes PowerShift automated transmission, computer-controlled air compressor and a governed coolant pump.

The fuel consumption test for the new Mercedes-Benz Actros, which was run under ideal conditions, was meant to show what state of-the-art vehicle technology can achieve. At the same time, measurements using a comparable truck were taken to show the various factors responsible for the difference in fuel consumption in the test and fuel used in everyday traffic on European highways.

The fuel consumption comparison demonstrated the effects of inadequate traffic infrastructure and a lack of traffic management, incorrect vehicle configuration, inadequate vehicle maintenance and actual driving style.

The measurements in Nardo confirmed the figures from the German Association of the Automotive Industry (VDA), which says the instantaneous fuel consumption of a 40-tonne trailer/tractor combination can triple if the vehicle is forced to stop twice every kilometre, instead of travelling unimpeded at 50 km/h (31 mph).

Daimler says truck drivers are faced with traffic jams on a daily basis, often the result of road capacity bottlenecks or accidents. The development of state-of-the-art traffic management systems could make a significant contribution to improving fuel economy.

Failure to spec aerodynamic equipment when purchasing the vehicle can see fuel consumption increase by 10 percent, says Daimler Trucks. Correctly adjusting the wind deflectors on the cab can improve fuel consumption by up to 4 percent.

Anticipatory driving offers additional potential savings between 10 to 12 percent. The test drives with the Mercedes-Benz Actros have shown that under optimum conditions the vehicle technology accounts for just about 60 percent of the fuel consumed by a 40-tonne trailer/trailer combination. Traffic conditions, topography, vehicle configuration and maintenance make up the various factors in the remaining 40 percent or so. Traffic planners, dispatchers, fleet decision-makers and drivers can influence many of these parameters, the company claims.