Abstract: In order to research fuel economy and emissions of ethanol-diesel blends, based on engine bench test and chassis dynamometer test, the fuel consumption and exhaust emissions of a 2-cylinder direct-injection diesel engine and a diesel passenger car in use were measured. The results indicated that without any modifications on the diesel engine, ethanol-diesel blends could proper improve fuel economy and reduce the emissions of smokes and NOX, but the emissions of HC increased. Besides, properly reducing the fuel supply advance angles was beneficial to improving fuel economy and reducing emissions. In the case of vehicle testing, which fueled with E10, the fuel consumption reduced at middle and high speeds, and also the emissions of PM and NOX reduced after the cold starting at normal temperature. Therefore, the research results can provide practical references for the improvement of fuel economy and characteristics of ethanol-diesel blends.