Each of the 45nm transistors in the upcoming 8-core Intel® Xeon® processor uses 1/7000th the power of the original 4004 transistors that Intel was manufacturing in 1971 - quite a statement in energy efficiency. If the fuel efficiency of automobiles had improved at the same rate, a car would get 200,000 miles per gallon. You could put one gallon in your tank when you first purchase a car and never have to stop at a gas station again for the life of the car, and still have plenty of fuel to spare. And each transistor today takes up 1/40,000th the area of the transistors in the 4004.
Source : http://www.hardocp.com/