On the way to Bonneville Salt Flats, I ran through Eastern Oregon in the middle of the night, to maximize the overall mileage for the trip, in the Superbeetle -- 34MPG.
One stop for gas in 1500 miles, plus top-ups on the side of the road.
Instead of rebuilding the engine that needs a refresh, I shall use the Mileage Motor I've had on the bench fo a decade. That should be good for 40MPG before any aero mods.