The plural form of motorist is motorists.

Who are motorists?

From Longman Dictionary of Contemporary EnglishRelated topics: Motor vehiclesmo‧tor‧ist /ˈməʊtərɪst $ ˈmoʊtər-/ ●○○ noun [countable] someone who drives a car SYN driver, → pedestrian 12,000 motorists were stopped for speeding in the police crackdown.

Does vehicle have a plural form?

The plural form of vehicle is vehicles.