Most modern cars are a lot more tolerant thanks to advancements in oil technology. But it is to a greater or lesser extent better to warm your car up, even if it's not immediately / apparently necessary to you.
It's a different story if you're pulling a heavy load and can't do anything about it. Then letting her warm up makes some sense. Most people don't do that.
The benefits to slow driving is that it also brings the drivetrain up to operating temps as well - it's no good if the engine's at a good oil temperature but the differential and gearbox is still icy. But even letting the car idle for 10-20 seconds so it can push oil around the block, fill the galleries and start filling the lifters/head will help extend the lifespan of an engine, and then combined with a slow initial drive to allow everything to come up to temperature you should be able to give the car a bit more life.
In -20 degree weather you won't accomplish much idling and should purchase an engine block heater if concerned.
Interesting article confirming what I am saying:
https://www.washingtonpost.com/news/wonk/wp/2014/12/29/the-b...
Again, twenty years of turning the car on, going inside for 15 mins, and coming out and sliding into a warm car.
I'm not anywhere near knowledgeable enough to explain the details. I am fairly certain however that I was not hallucinating this throughout my entire childhood and young adult years.
No. The engine, and thus the water, will heat faster under a driving load.
You can wipe condensation off, but I've always found it has a tendency to reappear quickly. Perhaps I'm wiping wrongly, but the only solution I ever found to work reliably is to leave the aircon and windscreen heater running until the inside of the windscreen has warmed enough to prevent immediate reoccurrence.
That's meant idling the engine in every car I've owned. Cabin heating never seems to run at full blast unless the engine is powering it...
It's absolute hell on the engine though. Don't do this with vehicles that you are responsible for. This is mostly only applicable for leased vehicles.
Modern cars, to a greater or lesser extent, aren't too bad with running on fresh startup due to modern oil technologies.
BUT. This is not a universal case. Large diesels like to idle up before operating. Performance cars (especially turbocharged cars) will live longer if you allow the fluids to warm up correctly. My race car will absolutely shit the bed if you don't warm it up before operating.
And to be fair, as far as mechanical sympathy goes, it always pays to warm up your car. It'll be the difference between the car going 100,000miles or 150,000 miles in a lot of cases.
Unless you've got a booming system with several large subwoofers, you aren't going to excessively drain your battery by listening to the radio with the ignition in the accessory position.
For A/C, take the kids inside. For dogs, park in shade and get an accessory window fan. On all but the hottest days (L.A., Phoenix, and similar places excepted) they'll be quite comfortable.
I leave my dogs in the car all the time. They're in the shade with great ventilation. They're unstressed and content in a space they consider home.
People freak out when a dog is contentedly sitting in a car on a 60F day. Don't be one of those people.
However, many vehicles are such configured that in order to have any amount of power available, you need to also power up the daylight running lights, fuel pump, internal computer and other consumers that quickly add up and can indeed drain a battery in a few hours. There needs to be more awareness from the car builders about the need for an eco, long lasting ignition option that you can safely use without risking battery discharge.
On almost all cars the aircon compressor is driven by the engine, not an electric motor, so the motor needs to be running to cool the air.
The fan that blows the air through the vents is electric, but the air coming out will only be ambient temperature if the motor isn't running.