This study looked into the outcomes of ethanol concentration on the power and efficiency of a Flexi engine. It was found that a mixture of iso-octane, n-heptane, toluene, and ethanol performed equally well as Brazilian petrol with a high oxygen content. The Fiat Fire 1.4L Tetra fuel engine was chosen for testing and was powered by a combination of CNG, regular petrol, Brazilian petrol (18%-27% v/v anhydrous ethanol), and conventional petrol. The results showed a lambda value of 0.9, peak power at 5500 rpm, and peak torque at 2250 rpm. The spark timing was altered to maintain 900 C as the maximum exhaust gas temperature, and the ignition timing was altered to obtain maximum power at WOT.