| R&O | Rust and Oxidation Hydraulic Fluids |
| RAM | Random Access Memory |
| RBOT | Rotating Bomb Oxidation Test |
| RCC | Remote Climate Control |
| RDS | Radio (broadcast) Data System |
| RECIS | Remote Entry Control and Immobilizer System |
| REDOX | Reduction Oxidation Catalytic Converter |
| RF | Radio Frequency |
| RHD | Right Hand Drive |
| ROM | Read Only Memory |
| RON | Research Octane Number |
| RPM | Revolutions Per Minute |
| RSC | Roll Stability Control |
| RUL | Regular Unleaded Gasoline |
| RV | Recreational Vehicle |
| RVP | Reid Vapor Pressure |
| RWD | Rear-Wheel Drive |
