How much should I disclose when selling my car?

Hey all!

I'm planning to sell my 15yo car. It's my first car and so it will be my first sale (hopefully). Just passed MOT for another year and works just fine apart from a couple of little things like:
- AUX cable needs to be in just at the right angle to work correctly or you only get one channel. Radio, Bluetooth, CD player, speakers - all works just fine otherwise.
- Driver's side heated seat not working, passenger side does.

My initial idea was to be upfront about all the little things when advertising it, but my dad says there is no reason to and no one is expecting a 15yo car to be fully working when it comes to little QoL things like that, as long as the main parts are fine. Also mentioned he never even used AUX cable or heated seats himself.

His advice is: when asked about them directly - be honest, but otherwise don't sell yourself short by needlesly mentioning what is not working and giving the other party bargaing power. Especially since we're selling it for under a thousand anyway.

What is the car sale etiquette here? Is he right? Or should I be proactive in mentioning the little defects?

Thanks!