Car driving aid that's being investigated? (7)

I believe the answer is:

auditee

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'being investigated?' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'car driving aid' is the wordplay.
'car' becomes 'audi' (Audi is a German car brand).
'driving aid' becomes 'tee' (I've seen this in another clue).
'audi'+'tee'='AUDITEE'

'that's' is the link.

Can you help me to learn more?

I've seen this clue in The Times.

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