Dear Tom and Ray:

I know it takes a lot of gas to start a car, but how much? How long would you have to let your car idle in order to use as much gas as it would take to start it? My sister's boyfriend told me two hours, but that seems like an awfully long time to me. Is he right, or do I get to rub your column in his face? Also, could I do any harm to my car in the long run if I did leave it idling for two hours?

--Andy



TOM: Rub away, Andy. Get that news print all over his nose. I'd say you use less than a minute's worth of gas when starting the car. Maybe a lot less. The notion that it takes some huge amount of gasoline to start a car is--like my brother's good looks--a complete myth.

RAY: Modern, fuel injected cars start so quickly and meter gasoline so carefully, that practically none is wasted on starting.

TOM: So if the only consideration were fuel, you would shut off your car everytime you stopped for more than a minute.

RAY: But fuel isn't the only thing you use when you start the car. You use up a little bit of battery life, you put some wear and tear on the starter and flywheel, and you run the engine for that second or two before the oil is at pressure and fully circulating.

TOM: So given all that, I'd say if you're stopping somewhere for three minutes or more, it's probably worth it to turn off the engine. You'll save gas and you'll cut down on pollution, with no real harm done to the car.

RAY: And would it hurt to leave your car running for two hours? Of course not. Haven't you ever seen a police car outside a Dunkin Donuts?