Dear Car Talk:
I deliver Meals on Wheels to seniors in my community. Should I leave my car running when I take a meal to the door, or turn it off?
Some stops are to the door and right back to my car. On other stops, I visit a little while, generally no more than five minutes. I live in Iowa, so some days, my heater is on, some days my air conditioning. Sometimes both in the same day. -- Jill
Whether you're delivering meals or babies, Jill, the answer is the same. You should shut the car off every time.
In the old days, when cars had sloppy, old carburetors and there were only three TV networks to watch, stopping and starting a car used more gasoline than letting it run briefly. So, in those days, if you were stopping for a minute, it didn't really make sense to shut off the engine.
But that hasn't been true since the 1980s. Now cars use computerized fuel-injection systems to precisely meter every drop of fuel, and there's absolutely no fuel penalty for stopping and restarting the car. On the contrary, you now use more fuel by letting it run. You also create more pollution by letting the car run while you're inside apologizing for the overcooked ham.
And you really don't need to worry about the starter or battery. They're durable enough to make many starts every day. In fact, newer cars with automatic start-stop systems are designed to restart hundreds of times a day.
As for your comfort, if you make a five-minute visit, the temperature inside the car is not going to change significantly in that time. Within a minute of restarting, the inside temperature will be right back to where you want it.
So, in my book, you're already an angel, Jill, for delivering meals for folks who need them. So go ahead and go for double-angel-plus status by reducing pollution and saving fuel during your deliveries.
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