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Vehicle with no special marks? (4)

Ross

I believe the answer is:

cars

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'marks?' is the definition.
Although both the answer and definition are plural nouns, I cannot understand how one could define the other.

'vehicle with no special' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'with' is a charade indicator (letters next to each other).
'no special' becomes 's' (common abbreviation as in Special Air Service. I am not sure about the 'no' bit.).
'car'+'s'='CARS'

Can you help me to learn more?

(Other definitions for cars that I've seen before include "Motor vehicles" , "Private vehicles" , "... when these may be driven?" , "Automobiles" .)

I've seen this clue in the Sydney Morning Herald.
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