I deliver home delivered meals. I have about 20 stops,. Most are for a few minutes. Is it better to turn off the motor or leave it running?
You’ll burn less fuel if you turn the engine off. Idling cars get ZERO mpg.
“If” the stop is for several minutes then turn off the engine. If it’s just for a couple of minutes then leave it running.
It is always best to shut it off and take the keys. A car can be stolen this way, and some insurance companies may deny a claim if the keys were left in it. Legally this is ‘taking’ not ‘stealing’ in some states. A difference between a misdemeanor and a felony. Also, your burning gasoline for no good reason and if a problem occurs with the engine running unattended, it could quickly become catastrophic and cause damage that might have been preventable.
In some places, it is actually against the law to leave a car running when you leave it.
Absolutely shut it off and take the keys. You risk having it stolen if you don’t. Do NOT underestimate what criminals will do.