The most common and most likely answer to this crossword clue is the 5 letter word LIMOS
I've seen this crossword clue in The Guardian
L
I
M
O
S
Buddy explains!

The straight part
We know that "Large cars" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case large cars = limos.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 LIMOS mean?
LIMOS noun- An automobile body with seats and permanent top like a coupe, and with the top projecting over the driver and a projecting front.
- An automobile with such a body.
- A luxury sedan or saloon car, especially one with a lengthened wheelbase or driven by a chauffeur.
- An automobile for transportation to or from an airport, including sedans, vans, and buses.