I want to start a list of cars that are exceptional in at least one important way, that improves efficiency.
Aptera 2e: exceptionally low aerodynamic drag with a Cd of 0.15 and a CdA of less than 3 (sq ft). Low weight (~1,700pounds) and drive train that is aimed at maximizing efficiency: it gets an equivalent of 200mpg on the EPA cycle. It seats two people side by side, and has plenty of storage capacity, and is supposed to be quite crash worthy.
VW 1Liter car: Nearly as aerodynamic as the Aptera with a Cd of 0.16, and probably a lower CdA, the prototype got ~264mpg US (0.89L/100km). It weighed just ~650 pounds! It seats two people one behind the other, and has limited storage capacity.
I have a copy of the Hucho book on car aerodynamics, and I will be making a 3D model of the Schlör Pillbug! I'll be happy to share it when I get it done.Maybach Stromlinienkarosserie (1939): Another streamlined car with a very low drag coefficient: 0.16 with flat windshield glass, and 0.14 with curved glass. Seating is at least 2, and may be 4 people. This car could go 150mph on just a 150HP engine.
Mercedes Bionic "Boxfish": A very interesting prototype based on the shape of the boxfish, which is counterintuitively very sleek. The prototype has a Cd of 0.19, seats four with adequate storage, and the structure is also based on the skeleton of the boxfish, which helps reduce weight and increase strength. With a diesel engine, this car gets ~84mpg US.
Toyota 1/X concept car: weighs just 926 pounds (curb weight) and carries 4 people. Can travel over 600 miles on 4 gallons of fuel. Is a plug in (serial?) hybrid with a 500cc ICE and a lithium ion battery pack. This is 150mpg+, folks!
Toyota 2010 Prius (3rd generation): A Cd of 0.25, and efficient parallel hybrid drive train, seats 5 with generous storage capacity -- it is in production now. It has been driven by a number of folks who managed to get 70+ mpg.
Toyota/Scion 2010 iQ: Soon to sold in the USA (already sold in Japan and in Europe), this little conventionally powered car has a Cd of 0.29, seats 3 adults and 1 child, and has very limited storage unless you have fewer people in the car. It gets 55+ mpg, and should cost ~$13.5K. It is under 10 feet long (only 10" longer than the Smart car), and is front wheel drive, has 9 air bags (1 behind the rear seat), and has very low emissions.
Honda 2009 Fit: Extremely flexible, roomy, and efficient design, mainly because of it's backseat. It is a good aerodynamic shape (though I do not have a Cd number), and can easily get in the 45+ mpg range, and probably higher if ecodriven well. It can seat up to 5 people, with several of them 6'-4" or taller.
Repeating what I wrote below, because I think it is very important:
All companies should use the year that a vehicle is sold as the model year. This takes the pressure off of making change for changes sake. It also (hopefully) will reduce the prevalence of planned obsolescence; and increase the durability and the recycle-ability of the materials used. All these things would greatly lower costs over the long run.
All design changes should be based on functional improvements. Imagine it: higher and higher reliability, better and better efficiency, continuous safety improvements, more and more recycled materials, design changes based on owner’s needs — what a concept!