TDI (engine)

Turbocharged Direct Injection, or TDI, is a name Volkswagen and its partner companies use for a certain type of diesel engine. These engines use a highly-pressurized fuel rail (over 2,000 bar/29,000 PSI) and intercooler to enhance the power gained from turbocharging an engine.^[1][2] These engines could be found in inline three, four, and five configurations, as well as V6, V8, and V10 configurations.^[3][4][5][6]

TDI engines have become controversial recently. This is because some TDI engines used a system to under-report their emissions of harmful gases during testing (at the cost of some performance and fuel economy), but were not sold in the emissions-defeating mode, which was a more powerful and efficient fine-tuning of the engine at the cost of more harmful emissions. This meant that the engine could put out up to forty times more nitrogen oxides than was legally allowed.^[7]