My 335i/M3 both defrost / deiced the front screen so quickly!
Really really impressed. Been -2C all night outside and neightbours were out there in the cold scratching for ages and I just sat in my car, heated seats, pressed that button for the front screen.
Typed an email on the phone, the song was in about 2:30mins and it was defrosted already when I used the wiper.
I don't know how it does it but I've never scratched the ice since owning the two BMWs.