Alternative fuels have gained considerable attention because of their excellent sustainable energy conservation and emission reduction characteristics. In this study, emission characteristics and fuel economy of three alternative fuels were compared for a passenger car under real-world running conditions. Specifically, the portable emission measurement system (PEMS) was used to evaluate the emission performance of 10 vol% ethanol in gasoline (E10), 15 vol% methanol in gasoline (M15), and liquefied petroleum gas (LPG). The results showed considerable variation in both gaseous and particulate emissions under different running conditions. Carbon monoxide (CO) and hydrocarbon (HC) emissions were higher on main roads, whereas particle number (PN) and particulate matter (PM) emissions were higher on expressways. Regulated emissions from the vehicle powered by three alternative fuels were lower than those of the vehicle powered by pure gasoline (G100). That is, the PN emissions of the three alternative fuels were 1–2 orders of magnitude less than those of G100, with a concomitant reduction in PM. Moreover, the proportion of nuclear-mode particles was reduced, with a maximum difference of more than 10% on expressways. LPG resulted in the cleanest gaseous and particulate emissions. M15 produced lower HC emissions than E10 because of its higher oxygen content, but led to higher carbon dioxide (CO2) and nitrogen oxides (NOx) emissions.