Turbocharged direct injection or TDI  is a design of turbodiesel engines offering turbocharging and direct injection of cylinder-fuel which was developed and produced by the Volkswagen Group (VW AG). These TDI engines are widely used in all major Volkswagen Group brands of passenger cars and light commercial vehicles manufactured by the company (particularly those sold in Europe). They are also used as marine engines in Volkswagen Marine and Volkswagen Industrial Motor applications.

Some TDI engines installed in the model year 2009 to 2015 Volkswagen Group cars sold through September 18, 2015 had an emissions defeat device, which triggered emission controls only during emissions testing. Emission controls were suppressed in another way, allowing TDI engines to exceed legal emissions limits. VW has admitted to using the illegal device on its TDI diesel cars.

In many countries, TDI is a registered trademark of Volkswagen AG.

The designation TDI has also been used in vehicles powered by diesel engines designed by Land Rover. These are not related to the Volkswagen Group's engines.