Ever lived in a cold environment? You idle to let your heating system get up to temp. I grew up in a cold area and no way was I going to jump in my car right away in -20 degree temps.
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.
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.