that is not necessarily true. The more power a processor takes in, the faster clock speed it can produce and vice versa. Although a new processor can be more efficient, it can produce more with a similar energy input. It is really up to the designers to decide how much power it will consume. If I had to guess they would choose the same amount, but honestly it can be anything, more or less power. It is not necessary for every new processor to take up less power.
Of course generally over longer periods of times, processors have been developing and use way less energy than previous models and produce higher benchmarks. just food for thought