Do cars burn more gas after a cold start on a wintery morning?
sierpnia 5
irobot10 asked:
After starting my drive at 5am, I see the smoke coming out of my car in the rear view mirror. The smoke disappears after the engine has reached its normal operating temperature. Similarly one can see smoke at the tail pipe of almost all cars coming out of various subdivisions in the morning. But no car on the highway has a smoke trail behind it. Hence the question - do cars burn more gas after a cold start until engine becomes hot enough?
After starting my drive at 5am, I see the smoke coming out of my car in the rear view mirror. The smoke disappears after the engine has reached its normal operating temperature. Similarly one can see smoke at the tail pipe of almost all cars coming out of various subdivisions in the morning. But no car on the highway has a smoke trail behind it. Hence the question - do cars burn more gas after a cold start until engine becomes hot enough?
Tags: 5am, Cars, Cold Start, Rear View Mirror, Smoke Trail, Tail Pipe
sierpień 9th, 2008 at 00:37
they burn a small amount of extra fuel, not much
what you are seeing is mostly water vapor (steam) until the engine is up to operating temp.
In the “old days” before computerized engine controls it was far worse, you could not be in a closed garage with a cold engine idling for more than a few minutes without your eyes watering.
Now with efficient engine control systems, modern engines do use a small amount more fuel for the first few minutes but it is far far better than it was.
sierpień 9th, 2008 at 06:35
what your seeing is condensation from a cold engine that’s heating up very quickly. Once all the components are warm it stops. But to answer you gas consumption question, it does burn more fuel when cold, doing this helps keep it from stalling until it’s warm
sierpień 10th, 2008 at 21:50
yes, they are much less efficient when they are cold…
sierpień 14th, 2008 at 05:16
Most cars will have a “high idle” when you first start them on a cold morning. There’s a sensor that checks the temp of the air being sucked into the engine. If that temp is too cold, it makes the engine run a little faster (just as if you had pressed down a bit on the gas pedal) until the engine compartment warms up. So, the difference that you’re probably seeing in the amount of “smoke” (exhaust) before and after your car warms up is simply due to a higher idle, and therefore more exhaust pressure - the hot air is moving faster out into the cold air, so it gets farther before it cools enough to “disappear”.
As for the “subdivision” versus “highway” difference, that’s probably more a matter of speed. For example - if you lit a cigarette (not that I’m encouraging anybody to smoke) and held it up to your window, you’d see more smoke if you were driving slow than if you were driving fast - same effect.
sierpień 16th, 2008 at 00:18
The smoke is actually condensation from the combustion process of gasoline. Very normal. It diminishes greatly as the various components of the exhaust system come up to normal temps.
Yes, cars do use more gas in cold weather, especially after start-up, but drops to near normal when the engine is at normal operating temps.
sierpień 17th, 2008 at 17:18
Personally I would have to say yes they do.