[danielharan]

It's an unproven proposition, and usually only applied to industry. If my refrigerator is more efficient, I won't buy a second one. A more efficient car might give me an incentive to drive more, but that seems really marginal.

[eru]

People who hadn't brought refrigerators before, might be a first one, though. And if there are extremely efficient, we might even switch to living inside refrigerators [1] in summer.

[1] Some people already do.