The most common and most likely answer to this crossword clue is the 8 letter word SCOOTERS
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result SCOOTERS
Buddy explains!

The straight part
We know that "Vehicles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vehicles = scooters.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SCOOTERS mean?
SCOOTERS noun- A kick scooter or push scooter; a human-powered land vehicle with a handlebar, deck and wheels that is propelled by a rider pushing off the ground.
- A electric version of the kick scooter.
- A motorscooter; a small motorcycle or moped with a step-through frame.
- A mobility scooter; an electric-powered scooter specially designed for disabled and/or elderly people.
- An ice scooter; a type of flat-bottomed, buoyant ice yacht used in the state of New York, equipped with runners for traveling over ice.
- Any of the large, black ducks of the genus Melanitta; the scoter.
- To ride on a scooter.