consider only the first use phase. Often vehicles with a performance of over 800’000 km are sold for further use in Europe as well. Therefore it must be assumed that many trucks continue to operate either in the country of first registration or in other countries. The life-time performance will therefore be well over 1’000’000 km, maybe up 1’500’000 km. The exemplification (Tab. 14) uses a life-time performance of 1.2 Mio. km. The life- time primary energy savings of the articulated truck example will be around 20 GJ for a 100 kg weight reduction.
Tab. 14: Overview of data for exemplification of articulated commercial trucks (50 % load)
Fuel consumption (l/ 100 km)
Specific fuel savings (l/ (100 km*100 kg))
Relative energy savings (%/ 10 %) Life-time performance (km) Life-time final energy savings (MJ) Life-time primary energy savings (MJ) Life-time CO2 savings (t) Source: IFEU 2002 from various sources
3.1 % 1’200’000 17’000 20’000 1.4
Weight limited cargo
Cargo vehicles will normally take a payload up to the maximum allowance if possible (e. g. 40 t for articulated trucks in Germany). In this case the weight reduction permits the transportation of a higher payload and thus less vehicle-km are needed to transport a certain amount of goods. Therefore not only the energy consumption due to weight dependent resistance factors is reduced, but the total energy consumption of the saved transport-km. Energy savings for weight limited cargo are therefore higher than energy savings for volume limited cargo.
A weight reduction by 100 kg also allows for a higher payload of 100 kg with the total weight, thus also the energy consumption per vehicle-km, maintained (Tab. 15). On the other hand 120’000 t-km transport performance can, based on the assumption of a constant maximum load, be saved during the life-time of the vehicle. This is the equiva- lent 4600 vehicle-km of fully loaded articulated truck with a fuel consumption of 40 l/ 100 km. This results in 76 GJ primary energy savings in this extreme case.
Net vehicle weight [t]
Maximum payload [t]
Life-time transport performance
Tab. 15: Life-time performance with different payloads
Source: IFEU 2002 from various sources
In this extreme scenario more than three times the direct energy savings could be achieved. [STODOLSKY et al.1998] concluded that a weight reduction of about 1t would decrease the fuel use of weight limited transport per t-km by more than 3 %. For