| TAC | Throttle Actuator Control |
| TAG | Technical Advisory Group (CMA) |
| TAN | Total Acid Number |
| TBI | Throtle Body Injection |
| TBN | Total Base Number |
| TBS | Tapered Bearing Simulator |
| TCC | Torque Converter Clutch |
| TCM | Transmission Control Module |
| TCS | Traction Control System |
| TCW-3 | Water Cooled 2-cycle engine oil specification |
| TDI | Turbo Diesel Injection |
| TEL | TetraEthyl Lead |
| TEOST | Thermal-oxidation Engine Oil Simulation Test |
| TFOUT | Thin Film Oxygen Uptake Test |
| TFSI | Turbo Fuel Stratified Injection |
| TGA | Thermogravimetric Analysis |
| THF | Tractor Hydraulic Fluid |
| THOT | Turbo Hydramatic Oxidation Test |
| TLEV | Transitional Low-Emission Vehicle |
| TMA | Truck Manufacturers Association |
| TMC | Test Monitoring Center (ASTM) |
| TME | Tall Methyl Ester |
| TML | Tetramethyl Lead |
| TO-2/4 | Caterpillar transmission oil specification |
| TO-4 | Caterpillar transmission oil specification |
| TO-X | Heavy-duty diesel engine oil specification |
| TOST | Turbine Oxidation Stability Test |
| TOU | Tractor Oil Universal |
| TPEO | Trunk Piston Engine Oil |
| TPS | Throttle Position Sensor |
| TPV | Tapered Plug Viscometer |
| TRD | Toyota Racing Development |
| TSI | Turbocharged Supercharged Injection |
| TT | Touring Turismo |
| TUV | Technischer Uberwachungs Verien |
| TWC | Three-Way Catalyst |
