Abstract This paper reports the quantification of the evaporative emissions from gasoline-poweredmotor vehicles in South Africa under various conditions including high temperatures. Three vehicles with and without evaporative emission control systems have been tested to quantify gasoline evaporative emissions, including both diurnal and running loss emissions. Measurements were made in a Sealed Housing for Evaporative Determination over a range of ambient temperatures. The standard diurnal test shows that evaporative emissions increase progressively with increasing fuel temperature. South African gasoline poweredmotor vehicles exhibitedevaporative emissions 10 times higher than that allowed by the United States Environmental Protection Agency. The extended-time diurnal test shows that the fuel emittedfrom gasoline-poweredmotor vehicles in South Africa is about 97 million litres of gasoline every year.