Volkswagen's quest for efficiency began well before lawmakers started linking emissions to fines. It sold several fuel-sipping, Formel E-badged models during the 1980s, and its research and development department took fuel economy to the next level by building a prototype named Öko-Polo designed to use only three liters of diesel per 100 kilometers, which represents about 78.4 mpg. One surviving prototype lives in New Hampshire.
Visually, little set the Öko-Polo apart from the regular-production variant of the second-generation Polo it was based on. It gained rainbow-colored stripes on both sides, and a roof-mounted spoiler borrowed from the Formel E, but nothing about these add-ons revealed the presence of a cutting-edge powertrain under the hood.
Power for the Öko-Polo came from a supercharged, direct-injected two-cylinder diesel engine with a displacement of 858 cubic centimeters. It made 40 horsepower, according to enthusiast website Polo Driver, and it gave the Öko-Polo a top speed of about 85 mph. Power was sent to the front wheels via a five-speed semi-automatic transmission; drivers still had to shift, but an electronic switch in the gear knob activated the clutch.
Even with 40 horsepower, a rounding error in Hemi-speak, the Öko-Polo wasn't as underpowered as it sounds because it was very light. Its engine was loud, however, so thick layers of sound-deadening material kept decibels in check in the cabin. In hindsight, everything came together beautifully, and the prototype exceeded expectations. It averaged 138 miles per gallon on a trip from Marseilles, France, to Wolfsburg, Germany.
One of the project's main goals was to reduce emissions, so engineers developed an exhaust gas recirculation system, a particulate filter and a coasting function, features that are common today, but which were nearly unheard of 32 years ago. They also fitted the Öko-Polo with a version of the stop-start system found in the regular-production Polo Formel E.
Volkswagen tested about 60 units of the Öko, and it consigned the project to the attic after gathering the data it needed. Series production was not seriously considered, partly because the hatchback would have cost too much to build, but some of the lessons learned later trickled down to production cars. Volkswagen notably released the Lupo 3L in 2000. It used three liters of diesel to cover 100 kilometers, like the Öko-Polo, thanks in part to visual modifications (including a more aerodynamic grille), the widespread application of weight-saving techniques such as thinner glass and alloy suspension parts, and a stop-start system for its 1.2-liter three-cylinder diesel engine.
New Hampshire-based enthusiast Ross Cupples keeps one of the surviving Öko-Polo prototypes in his personal collection of over 70 Volkswagen models. Shown in the gallery, it's still wearing its original rainbow-colored stripes and it hasn't lost its body-colored hubcaps. Its odometer displays about 6,172 kilometers, which represents roughly 3,835 miles. Its experimental engine is long gone, however, so Cupples dropped a gasoline-burning, 1.0-liter four-cylinder from a regular-production model behind the grille in order to drive the car.
Finding a second-generation Polo in the United States is unusual, the model was never officially sold here, but discovering a rare prototype is almost unheard of. How did it get here? Your guess is as good as ours; even Cupples doesn't know. He purchased it from a seller in Wisconsin who bought it from a government auction.