You're forgetting one; Triumph.
(The motorcycle one)
This may be a four-wheeled forum so we're all inclined to believe that cars are the way of the future and forget bikes, but bikes offer a lot more of the basic elements needed for good economy.
Admittedly, safety and load capacity are problems, but a bike with a more-complete fairing and (numerically) lower gears using a modern bike's platform would generate some astronomical fuel economy numbers.
EDIT: Bikes, unlike cars, have been getting lighter.