Yes, could be late-seventies when inflation was going nuts, and more government mandated equipment was being added to cars every year. New government regulations will be adding considerably to the cost of cars in the near future. Improving gas mileage means using higher cost materials and technologies. Economies of scale will help to offset some of that, though. If you put variable valve timing and direct injection on EVERY engine, the cost becomes a bit more reasonable. But aluminum insn't going to get any cheaper. And cars will be using more of it. Taking weight out of a car body structure for better mileage is tricky if you don't want to sacrifice passenger safety.
Gordon