IRVW II

The IRVW II, short for Integrated Research Volkswagen, was a research car that Volkswagen built in 1980 by modifying a Volkswagen Passat (B2) to study how little fuel an ordinary car could use. It had a 1300 cc engine, weighed 997 kg and reached a top speed of 160 km/h. The work was developed under Ulrich Seiffert by Ernst Fiala. Its best known idea was gliding: when the driver released the accelerator the engine shut down and the car coasted, then restarted when the pedal was pressed again, which the article says saved up to 2 litres per 100 km and was a forerunner of the start-stop system. A green indicator with an upward arrow told the driver when to shift up, and an Ecometer displayed consumption in litres per 100 km. The article records that gliding was not covered by the consumption and taxation rules, so the automatic engine shutdown did not reach production at that time.