| Abbreviation | Definition |
|---|---|
| OREP | Oldham Race Equality Partnership |
| ORL | Orion Racing League |
| ORP | Oregon Raceway Park |
| ORQ | Ocean Racing Queensland |
| ORQ | Ocean Racing Queensland Class Association |
| ORR | Offshore Racing Rule |
| ORX | On-line Racing eXtreme |
| OSRC | Ohio State Racing Commission |
| OSRR | Old Sandwich Road Race |
| OSRS | Ohio Spring Race Series |
| OTF | Open Trace Format |
| OTR | Oval Track Racing |
| OTTR | Off To The Races |
| OVT | Ocean View Terrace |
| OWR | Ollie Walker Racing |
| OWR | Ontario Watercross Racing |
| OWR | Open Wheel Racing |
| OWRA | Ontario Watercross Racing Association |
| OZR | Option Zero Racing |
| PARA | Pennsylvania Alpine Racing Association |