The Goggomobil Dart, a 1950s microcar from Glas, used a two-stroke engine with such primitive emissions that the manufacturers deliberately specified mineral oil that would only partially combust, leaving an oily residue that coated the engine internals to reduce wear—meaning owners were essentially supposed to foul their own spark plugs with incompletely burned oil as an intentional maintenance strategy to keep the tiny engine alive.
Car Fact #141 — November 3, 2026
