It's my understanding that the older ones, that actually got good milage, didn't have enough power and acceleration for Americans (I can't speak for anybody else). So the manufacturers, after hearing nothing but complaints, gave the cars more power, resulting in the lower milage.
I could be wrong on the reasoning, but if not, I agree that this seems pretty stupid.

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“Sometimes I think we're alone. Sometimes I think we're not. In either case, the thought is staggering.” - Buckminster Fuller

"A man talking sense to himself is no madder than a man talking nonsense not to himself." - Guildenstern, “Rosencrantz and Guildenstern are Dead”