I called half a dozen mechanics across half a dozen states and got recommendations that ranged from 0 seconds to 10 minutes.
It's not that cold out. Should I still be plugging in my car
How long should you allow for your vehicle's engine to warm up
Is It Necessary to Warm Up a Vehicle Before Driving?
Are There Benefits To Warming Your Car In the Winter?
The biggest winter energy myth: That you need to idle your car
The biggest winter energy myth: That you need to idle your car
Does Warming Up Your Car Actually Help?
Let there be heat: How long should you plug in your car, car plug
Let there be heat: How long should you plug in your car, car plug
Tips for your car in the cold: Inflate tires, check fluids, full tank
Caltex Singapore - How long do you warm up your car before you
Frigid? Mechanics say skip warming up your car's engine
Idling your car before driving—myth or fact?