This paper reviews the works done on ‘influence of compression ratio (CR) on the performance of spark ignition(SI) engine using fuel blends of ethanol namely E0 (gasoline), E25 (75% gasoline, 25% ethanol), E10, E20, E22, E50, E75, E100 for different CR. The main parameters considered for comparison were brake specific fuel consumption (BSFC), CR, brake torque (BT), air-fuel ratio (AFR) and exhaust emissions. The experimental results of various studies are compared. The need of advanced engine development techniques and modifications are also studied and emphasis is laid on the use of variable compression ratio (VCR) SI engine. The benefits of using VCR in the coming future are discussed briefly mentioning the challenges faced. It is concluded that gasoline-ethanol fuel blends increase the overall output of engine whilst reducing the harmful emissions and increasing engine reliability and life, at higher compression ratios and thus providing a new platform in the automobile sector for its further development.