We obtain the envelope curve of the bid functions for passenger car characteristics in Greece and use it to analyze the relationship between nominal and quality adjusted car prices over the 1965-1985 period. For its identification and estimation without imposing a priori restrictions we apply single- and multi-market approaches of the Box-Cox flexible functional form estimating technique in a modified version of Rosen's hedonic price model. On the empirical plane, the results show that (a) the quality adjusted prices of cars imported from Germany, France, Italy and Japan declined from 1965 to 1970 and increased continuously thereafter; (b) the quality of cars from France and Italy, and to a lesser extent from Japan, responded favourably following the two oil shocks, and (c) low priced cars offer more quality for the money.