So Honda has a new Insight hybrid, and almost every comment I have seen says that Honda "copied the Toyota Prius" shape. Not really. What both four-door hatchbacks do is follow the tenets of Reinhard Koenig-Fachsenfeld, a sometime motorcycle racer who lacked the academic credentials so important in German engineering circles. The talented German professor/doctor/engineer Wunibald Kamm, whose name is commonly applied to the truncated tail featured on both the Insight and the Prius, headed the Research Institute for Motor Vehicles and Engines (FKFS) in Stuttgart from 1930 until the end of WWII and lent his prestige to the development of Koenig-Fachsenfeld's aerodynamic patents. Together, they built and tested a series of experimental, Prius-like "K-cars" that were a far cry from the eponymous little boxes that saved Chrysler in the early 1980s.
The 1952 Borgward Hansa 2400 was, as nearly as I can tell, the first-ever production car to make use of the two men's research, but the K tail has surfaced from time to time in racing cars like the Cunningham C-4RK in the '50s. I did a Datsun study with Howard Assel in 1958 using the same principle of not allowing the boundary layer of air sweeping over the body to separate into turbulent flow until the absolute aft end of the roof.
But the best application, and the one I am sure influenced both Toyota and Honda, is the non-U.S.-market Audi A2 seen here, which was built from 1999 to 2005. Like our proposed Datsun, the body was aluminum - drawing on experience Audi gained building the first A8 sedan - so it was light, less than 1900 pounds in super-economical "3 Liter" form, despite meeting all safety norms. The "three liters" in the name stood for its fuel consumption - three liters per 100 kilometers, or better than 78 mpg, thanks to an aluminum, 1.2-liter, three-cylinder turbo-diesel making 60 hp. Skinny tires and a low-drag shape - Audi claims its 0.25 Cd makes the A2 the lowest coefficient-of-drag sedan ever mass-produced - allowed a top speed of 104 mph. I drove an A2 with a 74-hp, 1.4-liter diesel and found it very agreeable, achieving better than 50 mpg. When I needed to replace my daily driver two years ago, I looked for one, but the design is so well-suited to present conditions that used A2s are more expensive than roomier, brand-new cars from at least a dozen mainstream manufacturers.
Because it was odd-looking and very expensive for its size, only about 175,000 A2s found buyers in six years, so there really are not many available in the used-car market. Not to worry, though, as Georg Kacher, our all-but-infallible product prophet, says Audi is planning to make another A2 in 2013, this time with available Quattro all-wheel drive using an electric motor to power the rear wheels. Good. That's just about the time my present tin-box car will be up for replacement, so I won't have any problems finding an A2.