Audi is celebrating the 25th anniversary of the TDI engine by taking a look back at their iconic powerplant.

Audi is celebrating the 25th anniversary of the TDI engine by taking a look back at their iconic powerplant.

Originally introduced at the 1989 Frankfurt Motor Show, the 2.5-liter TDI five-cylinder engine produced 120 PS (88 kW) and 265 Nm (195 lb-ft) of torque. It enabled the Audi 100 to average 5.7 L/100km (41.2 mpg US / 49.5 mpg UK) and hit a top speed of nearly 200 km/h (124 mph).

Over past 25 years, the TDI engine has been improved and Audi says it has "seen its power and torque - relative to displacement - increase by over 100 percent." At the same time, emissions have fallen by 98 percent.

Audi currently offers 156 TDI models and TDI engines can be found in every Audi except the R8.

In the future, Audi will offer a plug-in hybrid with a TDI engine. The company's electric biturbo TDI engine will also be launched "soon."

Audi celebrates the 25th anniversary of their TDI engine [video]