In the present study, the effects of water addition into intake air (WAIA) on the engine performance and exhaust emissions have been investigated experimentally in an automotive spark-ignition engine (SIE) which is used in Renault Clio vehicles. Experiments have been performed for (3, 6, 9 and 12) % (by vol.) water ratios (WRs) at different engine speeds and different loads. Selected engine speeds were (3000, 4000 5000, and 6000) rpms. 6000 rpm is the maximum speed of this engine. Selected loads were (100, 90, 80, 70, 60, and 50) Nm for (3000, 4000, and 5000) rpms and were (80, 75, 70, 65 and 65) Nm for 6000 rpm, respectively. The test results showed that WAIA decreases significantly brake specific fuel consumption (BSFC) at (3000, 4000, and 5000) rpms, but it increases BSFC at 6000 rpm. The maximum reduction ratios of BSFC at (3000, 4000, and 5000) rpms have been attained at the levels of 28.27 % for 5.60 % WR, 4.160 for 2.67 % WR and 7.19 % for 9.00 % WR, respectively. WAIA generally decreases nitrogen oxides (NOx) and total hydrocarbon (HC) emissions at all of the selected operating conditions. At (3000, 4000, 5000 and 6000) rpms, the maximum reduction ratios of NOx have been reached at the levels of 37.80 % for 8.67 % WR, 58.21 % for 12.18 WR, 57.80 % for 12.17 WR and 66.17% for 12.12.WR, respectively. Approximately 9.40 % decrement in HC was achieved by WAIA at the selected engine speeds. Carbon monoxide (CO) emission decreases by applying WAIA at 3000 rpm whereas it generally increases at (4000 and 5000) rpms. Unlike other engine speeds, WAIA increases CO emission significantly at 6000 rpm. Approximately 9 % WR yields the best results for engine performance and exhaust emissions at all of the selected operating conditions.