| IAC | Idle Air Control |
| IAFM | Integrated Air Fuel Module |
| IAOGP | International Association of Oil and Gas Producers |
| IBP | Initial Boiling Point |
| IC | Internal Combustion |
| IC | Ignition Control |
| IC | Integrated Circuit |
| ICC | Intelligent Cruise Control |
| ICCS | Integrated Chassis Control System |
| ICE | Internal Combustion Engine |
| ICM | Ignition Control Module |
| ICP | Injection Control Pressure |
| ICS | Integrated Chassis System |
| ICWS | Intersection Collision Warning System |
| ID | Identification |
| IDI | Indirect Injection |
| IDI | Integrated Direct Ignition |
| IDM | Ignition Diagnostic Module |
| IEDIS | Integrated Electronic Distributorless Ignition System |
| IFI | Indirect Diesel Injection |
| IFO | Intermediate Fuel Oil (marine bunker fuel) |
| IFP | Institut Français du Pétrole |
| IFSM | Integrated Fuel System Module |
| IGN | Ignition |
| IHI | Ishikawajima Harima Heavy Industries (turbo manufacturers) |
| ILEV | Inherently Low-Emission Vehicle |
| ILMA | Independent Lubricant Manufacturers Association |
| ILSAC | International Lubricant Standardization and Approval Committee |
| IMA | Integrated Motor Assist |
| IMMO | Immobilizer |
| IMT | Intake Manifold Tuning |
| in | Inch(es) |
| INJ | Injection |
| I/O | In/Out |
| IPIECA | International Petroleum Industry Environmental Conservation Association |
| IPM | Integrated Power Module |
| IPR | Injector Pressure Regulator |
| IR | Infrared |
| ISC | Idle Speed Control |
| ISG | Integrated Starter-Generator |
| ISO | International Organization for Standardization |
| ITS | Idle Tracking Switch |
| IVCS | Integrated Vehicle Control System |
| IVDT | Intake Valve Deposit Test |
| IVIS | In Vehicle Information System |
| IVSC | Integrated Vehicle Speed Control |
