My winter routine..
Open car, start engine, switch on heated seats (and now I can also switch on the heated steering wheel 😎) switch on the heated rear screen and door mirrors.
Scrape windscreen and side windows clear
Get back in and drive away.
Car is pushing out warm air within 1 mile, seats are toasty warm...
Unless you are parked on private land (driveway) it is an offence to leave a car unattended with the engine running.