Before we get into those cars with impressively big gas tanks, it's worth creating a frame of reference. On one side are the diminutive runabouts like the Mitsubishi Mirage and its 9.2-gallon tank.

There's nothing quite like the freedom of the open road on two wheels. You've got the perfect route planned, the scenery is amazing, and you're miles from anywhere. And then you see it: the dreaded, ...