The car care company tested how familiar 702 drivers were with a modern car engine.
Respondents were shown an image of an engine and asked to point out where they could find the screenwash reservoir (A), oil cap (B), coolant reserve(C) and dipstick (D).
While 79% of respondents identified all elements correctly, one in five motorists failed.
Over half of those who answered incorrectly confused the screenwash reservoir with the coolant reserve. 3%of motorists would make an expensive and potentially dangerous mistake of filling their screenwash reservoir with motor oil. 2% would put coolant liquid in their oil reservoir; an action likely to cost them a new engine.
Comma also asked motorists how often they top up their cars with oil. 60% of motorists check before leaving on a long journey. Two in five would take spare oil with them.