Lightweight construction has long been a requirement for coachbuilders, coupled, of course, with reinforcements for better safety and a more stable basis for the suspension. And if the corresponding specifications are met, the saved kilos are eaten up by more and larger comfort systems. But seriously, what would you estimate, how much savings would be 100 kg less curb weight, 0.2, 0.5 or even 1.0 liter per 100 km?

There exists a model calculation of the 'Automobiltechnischen Zeitung' of 08/11. The test cycle at that time was nothing else than the NEDC with a length of more than 11 km. A possible vehicle was taken from the C-segment (picture) with 1300 kg incl. driver. It becomes a c_W-value of 0.35 at 2 m² cross-sectional area, an air density of 1.19 kg/m³ and a coefficient assigned to the rolling resistance of 0.01.

After complicated calculation in the petrol engine the simple NEDC cycle results in 0.15 l/100km and the Diesel engine in 0.12 l/100km. Less consumption in general leads to less saving in this case. However, with the new WLTP cycle, with its significantly reduced idle time, greater accelerations and higher speeds, the savings would be higher for both.

Applied to all-wheel drive, this means in any case already 0.1 l/100km more consumption, at least for the lightest one. If it can be switched off, less is added than with permanent 4WD. If you are interested in a not as good as above validated number: a VW Tiguan was measured with 0.6 l/100km difference 2WD to 4WD. 02/18