| DAC | Downhill Assist Control |
| DAB | Driver Airbag (module) |
| DASMIN | Deutsche Akkreditierungsstelle Mineralöl GmbH (D) |
| dB | Decibels |
| DC | Direct Current |
| DCT | Dual Clutch Transmission |
| DDC | Detroit Diesel Corporation |
| DDS | Deflection Detection System |
| DEC | Digital Electronic Controller |
| DEER | Diesel Engine Emission Reduction (Conference) |
| DEOAP | Diesel Engine Oil Advisory Panel (API/EMA) |
| DETA | Diethylene Triamine |
| DEXRON | General Motors ATF specification |
| DFI | Direct fuel Injected |
| DGMK | Deutsche Wissenschaftliche Gesellschaft für Erdöl, Erdgas und Kohle e.V. (D) |
| DGI | Direct Gasoline Injection |
| DHYCA | Direction des Hydrocarbures et des Carburants (French Ministry of Industry) |
| DI | Detergent Inhibitor |
| DI | Direct Injection |
| DIFF | Differential |
| DII | Diesel Ignition Improver |
| DIN | Deutsches Institut für Normung |
| DIS | Direct (aka Distributor-less) Ignition System (replaced with EI) |
| DLC | Data Link Connector |
| DME | Dimethyl Ether |
| DMSD | Drive Motor Speed and Direction |
| DNR | Dolby Noise Reduction |
| DOC | Diesel Oxidation Catalyst |
| DOCP | Dispersant Olefin Copolymer |
| DOHC | Double Overhead Cam (twin cam) |
| DOT | Department of Transport |
| DPF | Diesel Particulate Filter |
| DPFE | Differential Pressure Feedback EGR |
| DPMA | Dispersant Polymethacrylate |
| DPNA | Diesel Particulate NOx Reduction (Toyota) |
| DRL | Daytime Running Light |
| DSCC | Distance Sensing Cruise Control |
| DSDA | Dual Stage Driver Airbag |
| DSG | Direct Shift Gearbox |
| DSP | Dual Spark Engine |
| DSS | Downshift Solenoid |
| DTBP | Di-Tert-Butyl Phenol |
| DTC | Diagnostic Trouble Code |
| DYNO | Dynamometer |
