The most common and most likely answer to this crossword clue is the 16 letter word AIR-CONDITIONING
I've seen this crossword clue in Independent
A
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Buddy explains!

The straight part
We know that "Car feature" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case car feature = air-conditioning.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 AIR-CONDITIONING mean?
AIR-CONDITIONING noun- The state of temperature and humidity produced by an air conditioner.
- An air conditioner or system of air conditioners.
- To mechanically cool a space or an entire structure.