Sure, but where do we stop? At the customers electricity socket? Behind all power supplies, but before the specific device? Computers will turn essentially all

Sure, but where do we stop? At the customers electricity socket? Behind all power supplies, but before the specific device? Computers will turn essentially all power entering them into heat. But then by that measure we can never make an efficient computer but would have to look at something like flops/W to give us actionable information. What is a measure we can apply consistently to computers and cars and get actionable information?