- oil way
- oil seal
- oilpan gasket
- operating piston
- operative
- opposed cylinders
- opposite lock
- optical check
- oil change
- oil filter
- oil level
- oil pan
- oil pressure
- oil separator
- oil sump
- oiler
- optional equipment
- organic
- outboard
- outer envelope
- outer headlight
- outer terminal
- outlet
- outlet pipe
- outlet side
- outlet valve
- outline
- output shaft
- oval piston
- over-inflation
- overcharging
- overdrive
- outer electrode
- overreving
- overrun
- oversteer
- oxyacetylene welding
- oxygen corrosion
- paint system
- painting line
- pair system
- overflow pipe
- overflow port
- overhang
- overhaul manual
- overhead
- overhead valve
- overrev
- oversteering
- oxalic acid
- oxygen sensor
- ozone
- packed gland
- palladium
- panel
- panel beater
- panel flanger
- panel puller
- paint
- paint booth
- paint shop
- paint stripper
- panel beating
- panel cutter
- panel hammer
- panel picking
- parallel key
- parallel twin
- paneling
- parallel circuit
- parallel valves
- parking bay
- parking brake
- parking heater
- parking lamp
- parking light
- parking pawl
- parking space
- part load
- part number
- part out
- part panel
- parts catalogue
- passenger car
- passive safety
- pastern noise
- patch panel
- patching
- pattern panel
- pawl
- PE headlight
- peak revs
- pedal clearance
- pedal travel
- pedals
- peen hammer
- peak power
- pedal
- peening
- performance