The engine performance and exhaust emissions characteristics of an internal combustion engine using three different fuel efficiency devices, namely Hiclone, Supermax and FFC are analyzed compared and discussed in this paper in order to identify the best fuel efficiency device among three. The testing was done in a 2.4L 4-cylinder Toyota Camry 2AZ-FE engine. The procedure recommended by Environmental Protection Agency (EPA) Aftermarket Retrofit Device Evaluation Program was used for engine testing. All the results obtained were when the devices were fitted and compared with results when no device was fitted with the engine. This study found that there is no significant increase/decrease of brake power, brake torque, fuel consumption and exhaust emissions for these fuel efficiency devices. Further study is recommended in order to come to an acceptable conclusion.