The most common and most likely answer to this crossword clue is the 9 letter word THROTTLES
I've seen this crossword clue in Financial Times
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More clues leading to the result THROTTLES
Buddy explains!

The straight part
We know that "Features of engines" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case features of engines = throttles.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 THROTTLES mean?
THROTTLES noun- A valve that regulates the supply of fuel-air mixture to an internal combustion engine and thus controls its speed; a similar valve that controls the air supply to an engine.
- The lever or pedal that controls this valve.
- The windpipe or trachea.
- To cut back on the speed of (an engine, person, organization, network connection, etc.).
- To strangle or choke someone.
- To have the throat obstructed so as to be in danger of suffocation; to choke; to suffocate.
- To breathe hard, as when nearly suffocated.
- To utter with breaks and interruption, in the manner of a person half suffocated.