It's December 1979, the Shah of Iran is out, insurgents are holding diplomats hostage at the U.S. embassy in Tehran, and the country has cut off oil shipments to the U.S. Spot gasoline shortages in parts of the U.S. have refocused public attention on fuel economy. In an effort to drum up sales for its large cars, Chevrolet takes the wraps off of a new Impala SE (special economy) that it claims is the first full-size car to boast a 20-mpg (11.8 L/100 km) rating, up from 19.3 mpg (12.2L/100 km) for the regular Impala. But the added fuel economy isn't cheap. The SE, at $6,291, costs $112 more that the standard model.