[windy1603]

If you have heated mirrors and no separate button for the mirror heating then they are on when heat screen is active (its was a way to save a few cents or euro by removing the mirror heating switch)

 

[windy1603]

No they have a switch for heated rear window which switches on the rear screen and mirrors.

Some earlier Peugeots had a separate button on mirror controls to switch the mirror heating on independent of the heated rear screen and it got deleted on later models to save money

 

[windy1603]

I thought my old 807 had a separate switch, I maybe confused with an older car I did have a MK3 Cavalier as well so it may have been that.