The First Vehicle With A Direct-Injection Diesel Engine May Be Older Than You Realize - Jalopnik

The origin of direct-injection diesel predates popular car applications by decades, with MAN in Germany leading the early development in the 1920s. Long before turbochargers, MAN eliminated the bulky air compressor by using airless injection, delivering fuel under high pressure directly into the cylinder head. This allowed diesel engines to move from stationary plants into trucks and, later, passenger cars. Though enthusiasts often point to 1989's Audi 100 TDI or 1986 Fiat Croma TD iD as early road-going examples, the broader history traces back to 1924 Germany, when MAN's approach laid the groundwork for modern direct-injection diesel technology.