Mercedes-Benz buses and coaches have now been approved for use with alternative fuels as per the prEN 15940 Directive. This includes the following sub-groups: hydrotreated vegetable oil (HVO), biomass to liquid (BTL), gas to liquid (GTL) and coal to liquid (CTL). These are various resources that are converted to fuel as part of chemical processes. The approval affects the OM 936 and OM 936 h (7.7 l engine capacity), OM 470 (10.7 l) and OM 471 (12.8 l) engines, from February 2016 in each case. The approval also applies to the most recent generation of OM 470 and OM 471.