The advantages of vegetable oil-based biofuels using in diesel engines have been demonstrated. Methods for determining
of optimal composition for mixed fuels containing petroleum diesel fuel and methyl ester of rapeseed oil have been
proposed. Optimization calculations of such mixed fuel composition for a type 245.12С diesel engine have been carried
out using the proposed methods. It has been shown that a mixture containing 60 % of petroleum diesel fuel and 40 %
of methyl ester of rapeseed oil has the best ecological characteristics among the researched mixed biofuels. Even better
ecological characteristics are reached when such mixture’s ingredients are regulated according to changes of the engine’s
shaft rotation speed and load.