That’s an old phrase that came out of the Jimmy Carter days when he pissed off the Arabs. If everyone saved 10mpg it would only drive down demand, lowering the price that the Chinese have to pay for their oil, allowing them to buy more. Saving 10mpg does little to help America.
A better strategy for the US is to drive the world wide price of oil up then get some kind of kickback from the suppliers, which would crimp the growing Chinese economy. Another option is invest in biotechnology that converts our massive coal deposits into oil.
If we were totally energy independent from OPEC, don’t think you’d get oil products any cheaper than the world price. Domestic suppliers divert their oil to the highest bidder, so you’d soon pay the same.
The technology to convert coal to diesel has existed since WWII. It's called coal gasification.
Nazi Germany ran their war machine on that diesel. And South Africa used to do the same.
And since America has some of the world's largest supplies of coal, what do we do?
Ignore it and buy $68 a barrel oil (which is a good deal higher than the break even profitability point for coal gasification).