Neil Vorano:

In 1989, the Volkswagen group debuted its first turbocharged direct injection (TDI) engine at the Frankfurt Motor Show under the hood of an Audi 100. It was revolutionary, with good power and good fuel economy at 5.6 litres/100 kilometres combined.
 You could say the engine was ahead of its time; nine years to be exact. Because almost a decade later, the European Union and the European Automobile Manufacturers Association would agree to lower CO2 emissions on its roads with tax exemptions that made diesel more cost-efficient than gasoline.