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.

The battery-electric BMW i7 gets a lot of flack—all deserved—for its monstrous fascia. Anchored by optionally illuminated flared nostrils that resemble a saiga antelope’s, bounded by the drooling ...