The most notable contrasts are that buyers of leaded gasoline are poorer than unleaded buyers and are somewhat less likely to use a credit card.'^ The income differences seem to widen substantially between 1980 and 1984. Buyers of leaded gasoline do not seem to make consistently smaller or larger purchases than unleaded buyers, and in no case do average purchase sizes appear to differ by more than 10%. The average age of buyers does not seem to differ substantially.