Innovation and Technology

Research Association for Automotive Technology (FAT)

The heaviest part of an automobile is the autobody, comprising about 40 percent of the total weight. If CO2 emissions caused by traffic are to be further reduced in the future, lighter constructions and thus new ideas in autobody construction are needed.

In the Research Association for Automotive Technology (FAT), all German car and commercial vehicle manufacturers and numerous suppliers come together under the umbrella of the VDA, to conduct precompetitive and joint research. Projects by research partners at universities, public research centers or non-university research and development services are carried out on its behalf. Since its founding, the FAT has published around 300 volumes on its research projects.

Reduction of parking search traffic in city centers

Scarce parking space and highly strained infrastructures lead to, in many cities, higher levels of parking search traffic. This unnecessarily generates waste gases, noise and loss of time. A new study by Prognos AG, on behalf of the Research Association for Automotive Technology (FAT), has recognized this and studied parking search traffic from cars and light trucks in city centers. In addition, the study aims to show how unnecessary parking search traffic can be reduced through better information.

Overall, by the estimate of the authors of the study, 560 million hours are consumed every year in Germany in parking search traffic. Parking places are sought, especially on leisure trips, round trips to the home and service trips. At least onefifth of all travel in business dealings is estimated as being related to parking search traffic. In private transport, it goes up to as much as about every other trip. 

The parking spaces and what information was available on their occupancy status were studied. It included parking garages and private parking spaces that are publicly available. This also included public road space, which is managed with parking ticket machines, parking meters or so-called “Handyparken.” The study concluded that in the car garages very good information was usually provided regarded open parking spaces. However, this information is only available in a very rudimentary fashion on the public streets. And this is regardless of the fact that management of this is possibly through parking ticket machine providing information on open parking spaces. Because wherever parking is managed, there is data on the parking tickets sold. However, this information has rarely been used for traffic control. Even in unmanaged public street space, it would be possible to provide information. The local authorities could use statistical methods, which in turn would permit information on its utilization.

If it is possible to greatly improve the information situation, the search for parking and the loss of time in German cities could be significantly reduced. The Prognos study came to the conclusion that, at best, up to 181 million hours of parking search time could be avoided. Less parking search traffic would also mean that the motor vehicle mileage could be reduced overall. By achieving the optimum possible savings of approximately 2.7 billion vehicle-kilometers, then around 0.5 million tons of CO2 could be prevented. The study shows that better information on the parking space availability could considerably reduce search traffic. To perform this for public parking space, usage forecasts are made and published using statistical and dynamic data from the parking ticket machine. The detection of individual spaces by sensors should be intensified. This data should be provided and publicly made available facility-wide over a data platform. 

The study on “Information about available parking spaces in cities” has been published in FAT Series No. 271.


Common passenger car parking space at home, average values


Garage, car port, private parking space

Public area


Large city (large) >500 kI (n = 6)

58 %

39 %

3 %

Large city (small) 100–500 kI (n = 14)

64 %

34 %

3 %

Medium city (large) 50–100 kI (n = 5)

70 %

27 %

3 %

Medium city (small) 20–50 kI (n = 9)

81 %

17 %

2 %

Small city (large) 10–20 kI (n = 9)

83 %

14 %

3 %

Small city (small) <10 kI (n = 6)

84 %

14 %

2 %


73 %

25 %

2 %

Source: VDA

Energy-efficient road train

The reduction of CO2 emissions is one of the major economic and technical challenges in road transport. The commercial vehicle industry is working intensively to further improve the energy efficiency of commercial vehicles. In addition to optimizing the powertrain, it is all about the sustainable reduction of aerodynamic drag and rolling resistance, which accounts for roughly 25 percent of the fuel consumption of a truck in long-distance traffic. 

To explore how driving resistances in heavy commercial vehicles can be reduced in the future. The Research Association for Automotive Technology (FAT) has launched a cross-manufacturer and precompetitive project on the “Potential analysis of an energyefficient road train.” The research should provide input on resource conservation in road transport for more economy in terms of energy efficiency in road traffic. In addition, the research project also supports the work on the future CO2 legislation on heavy-duty commercial vehicles and the revision of the guidelines on weights and measures (96/53 EC).

In it, the aerodynamic potentials of road trains were tested, for example, in extensive computer simulations. This was supplemented by flow tests in wind tunnels with semi-trailer models. The research showed that the greatest potential for aerodynamic optimization existed in the semi-trailer itself. Through side panels, tailgates and a downdraft tailpiece, approximately 5 percent more fuel could be conserved. Other types of semi-trailers can attain significant drag reduction by closing the space between the cab and the trailer. 

Using an articulated train, the air resistance can be greatly reduced if the gap between the two structures can be closed off from the penetrating air stream. This could be achieved by externally provided spoilers at the end of each trailer structure. These components are, however, only used to a limited extent, even under the future legal framework. An extension or alteration of the cab would impact with another 1 to 2 percent fuel saving. 

The rolling resistance of commercial vehicle tires was first practically tested on roads with specially created measurement vehicles. The research showed that the tread depth of the tires and the ambient temperatures have a strong influence on rolling resistance. Different rough road surfaces seem to be less of an influence on rolling resistance than as the case with passenger car tires. Super single tires on the drive shaft are particularly efficient. They produce 16 to 18 percent less rolling resistance than dual tires.

It also studied how rolling resistance can affect an entire road train. It became clear that, for example, the rolling resistance of a train that is loaded with a strong deviation from the ideal axial positioning can increase by more than 4 percent. In a fully loaded truck, the rolling resistance can, in turn, be reduced by 8 percent if the trailer is loaded with optimal weight distribution. For this, a payload-dependent load distribution plan was developed. 

To capture the full range of the above-described studies in the practical operation of road trains, several road trains – equipped with extensive measurement technology – are being monitored in their daily use. This new research project is funded by the German Federation of Industrial Research Associations. Based on the results that are expected at the end of 2016, simulation tools and analysis methods will be further developed. 

Under the FAT research project for energy-efficient road trains, numerous papers have been published: Heavy-duty commercial vehicle configurations under the influence of realistic flow conditions (FAT 281), Sensitivity analysis of factors in rolling resistance in commercial vehicles (FAT 258 and 279), Aerodynamics of commercial vehicle combinations under realistic driving conditions with crosswind influence (FAT 260), Examination of the rolling resistance of tires for commercial vehicles under actual road conditions (FAT 255), Aerodynamics of heavy-duty commercial vehicles (FAT 241), Consumption reduction of commercial vehicle combinations by aerodynamic measures (FAT 237).

Dr. Friedrich Preißer
Dr. Friedrich Preißer Head of Department German Association for Research on Automotive Technology (FAT)

Tel: +49 30 897842-310 Fax: +49 30 897842-600
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