The main aim is to gain summary of knowledge with necessary background data to operationally optimal ecological and economically efficient utilisation of gaseous and liquid fuels and sustainable biofuels in diesel engines of tractor – pullers with built-in dual system run simultaneously on these fuels. Subsequently to propose measures to further reducing of emission factors expressing the real specific GHG emissions of the verified biofuels and calculated according to standard method in accordance with EU and national legislation to achieve their savings higher than 60% compared to diesel.