Due to the health consequences of lead exposure, as well as to the introduction of catalytic converters, many countries have reduced or eliminated use of lead additives in motor gasolines. But in many other countries, leaded gasoline remains the norm. In these countries there is often confusion about the health significance of gasoline lead, the ability of cars to use unleaded gasoline, and the costs of unleaded gasoline. This chapter shows that leaded gasoline is a major source of human lead exposure. All cars, with or without catalytic converters, and with or without hardened exhaust valve seats, can use unleaded gasoline exclusively. Unleaded gasoline typically costs on the order of $0.01 more per liter than leaded gasoline to produce. Recent concerns about benzene exposure from unleaded gasoline have been addressed through choice of gasoline formulation and other measures.