An increasing share of the biofuels in the diesel is manifested by increasing specific fuel consumption. The lowest minimum specific fuel consumption (Table 4) 250.6 g (kW h)-1 was achieved with the diesel fuel containing 5.5% rapeseed oil, while the highest minimum specific fuel consumption of 286.8 g (kW h)-1 was achieved when the pure RME was used. The area of the low specific fuel consumption remained always the same. The engine rotation speed
ranges from1,530 to 1,630 min-1 and the load can be found near the rated engine speed characteristics.