What is illogical about it is that it is not fact. We would not cut our consumption of oil in have by cars getting two times better mileage. Why? Because automobiles run off of gas or diesel for the most part. Out of a 42 gallon barrel of oil, only 23 gallons of gasoline is refined. Diesel/fuel oil is also a product. But many other chemicals come out of that barrel.
Secondly, automobiles are not consuming all the gas or diesel. Trains, trucking, power plants all run off of diesel. Airplanes basically run off of kerosene, a derivative of crude oil.
You want to make a dent in oil comsumption, do something significant. Convert all our electrical demands to being supplied by Nuclear power. Wind energy where it is viable. And solar if it is practical.
That would be a good first step.
Electrical generation is an insignificant use of the US oil demand. Cutting this market in half would not be noticed at the gas pump.