I was listening to Click & Clack and somebody called in with a transmission problem. Their 4th gear went out, but their mpg's went up coz they went straight from 3rd to 5th. I tried this myself, skipping 4th as much a possible, taking it easy, not jumpin on it, and I got 19.6 mpg. Click & Clack referred to this as the European style of driving, to get into the highest gear asap without lugging. IDK what it's called, but I thought 19.6 was pretty good for my X.