The fuel consumption flow rates are measuring accordingly from two flow meters and also from the chassis dynamometer in advance mode. Brake specific thermal efficiency could be calculated from fuel consumption, times, power input and power output of different fuels from further mechanical analysis of the real engine performance parameter. For the performance test, the experiment begins with mainly double checking on safety practices of both diesel operation and HCNG DDF operation ensuring no leakages of any sort of hazard and dangerous fuels were leaking during the test and afterward. Then run only in diesel mode on chassis dynamometer to collect initial data for diesel operation three consecutive times. Horsepower, torque, fuel consumption and etc. were measured in three consecutive events on pure diesel operation to ensure accuracy of correct results in this experiment. The computerize system of chassis dynamometer will print out reports on each desire performance parameter against different RPM from the lowest to the highest possible for review and references. Afterward, the vehicle will be entered into HCNG diesel dual fuel mode and will run on the same test three consecutive times while performance data were collecting for further analysis of performance between pure diesel operation and HCNG diesel dual fuel operation. The printed report of HCNG DDF operation were collected after three consecutive tests had been done with accuracy.