Six gasoline blends were formulated using reformate, isomerate and light naphtha, the main gasoline refinery streams produced in Egypt. Ethanol was blended in the formulated hydrocarbon gasolines at levels of 0.0, 3.0, 5.7, 7.7 and 10.0 volume percent, which meet 0.0, 1.11, 2.14, 2.87 and 3.70 percent-by-weight oxygen, respectively. Thus, seven elthanol-gasoline blends were also formulated using ethanol as an oxygenating additive and octane enhancer. The effects of ethanol addition on Reid vapour pressure (RVP), antiknock quality and tailpipe exhaust emission of the oxygenated and non-oxygenated gasoline blends, were investigated. The employed test-vehicle was a Sahin Car type 1.4S, Model 2001;4 cylinders and 1400 C.C. engine capacity. The test-vehicle was prepared in strict accordance and emission tests were conducted using a portable Sun Gas Analyzer MGA 1200. Idle speed, 660-690 rpm, was measured using fluke800. The obtained results reveal that adding ethanol to hydrocarbon gasoline, in amounts ranging from 3.0 to 10.0% by volume, increases the RVP of the resulting blends by as much as 1psi. The results also show that the impact of ethanol on RVP and octane number varied depending on the blend's composition and ethanol content. Adding 10 volume percent ethanol increases RVP of reformate, isomerate and light naphtha by 1.52, 1.12 and 1.22psi, also increases the octane number by 2.0, 3.4 and 3.9, respectively. Concerning tailpipe exhaust emissions, the obtained results showed that the addition of 5.7% by volume ethanol reduces tailpipe exhaust emissions of carbon monoxide (CO) and hydrocarbons (HC). The effect on exhaust emissions of nitrogen oxides (NOx) is more variable, but at this ethanol concentration which meets 2.1% by weight oxygen, NOx emission has shown generally to decrease.