https://www.pcmag.com/news/linux-is-now-on-mars-thanks-to-nasas-perseverance-rover

You are absolutely not supposed to do that. In fact, you’re supposed to do the opposite. Letting your car idle to warm up kills it faster because the oil pump isn’t running because the car isn’t moving.

That is absolutely not true. The engine runs the oil pump, so the pump is working as long as the engine is spinning, assuming the pump is not faulty, of course. I’m not aware of any car engine ever built where that isn’t true.

That being said, idling your (modern) car for longer than a minute, or as long as necessary to defrost the windows in the winter, is a waste of fuel and, consequently, emissions. It’s also an unnecessary wear on mechanical parts, but not because the engine is cold or hot, but simply because it’s in use.

https://www.consumerreports.org/cars/cars-driving/should-you-warm-up-your-car-before-driving-a5580016349/

The question is $2 per person per meal. So unless you are eating that whole loaf of bread by yourself, you can spend $3 on it and use a couple of slices per person, which would only be a few cents.