Why does a car have better gas mileage in cold weather than in hot weather?

Question

I remember learning about this in physics class, but I have forgotten the reason. Please explain. Thanks.

Answer 1

I think it is correct to say that the efficiency of any heat engine improves as the temperature difference of the engine and the surroundings increases but there is another explanation that has to do with modern cars. Most cars today are equipped with air conditioning. Air conditioners take power from the engine and so reduce a car's mileage. We only run our ACs. in hot weather. In cold weather we warm are car's interior with engine heat that would otherwise go to waste. This gets us back to the original explanation. The car's heater acts as a second radiator giving engine heat an extra path to escape. In earlier times when climbing a steep hill in warm weather it was sometimes helpful to run a car's heater to get a little more power out of the engine. Anything you can do to keep an engine cool will improve its power output or its efficiency depending on how you drive.

Answer 2

In theory (and I stress "theory") the cold air is denser and simply provides a larger volume of air to the engine - increasing its power and efficiency. This is why race cars always run the strongest on a cool evening vs. during the hot day.

However, in reality (I live in Maine), the oil is thicker, all of the moving parts require more energy to move, you need a short warm up period before driving away, any snow or slush on the road requires more energy to drive through and short trips never completely allow the engine to reach full operating temperature - thus it runs richer. In short, in the real world, people get significantly poorer mileage in the winter around these parts than in the summer.

Answer 3

You have not only forgotten the reason, you got the conclusion backwards as well. Cars get better mileage in hot weather for several reasons, including less air drag and less oil drag.

Answer 4

I think it has something to do with the difference in temperature before and after combustion, or whatever. I don't remember exactly, but the greater temperature difference of before and after, the more efficient an engine is. That maybe explains it.

Answer 5

Cool air is dense with little moisture in it. As it enters the engine, it is warmed, making it ready to obsord much fuel, making for a very efficient fuel/air mixture (perfect for combustion). The warmer summer air has more moisture in it, and can obsorb less fuel, still adequete for combustion, but not as efficient.

Answer 6

To my knowledge from what I know, cooling the engine makes it run more efficient. Just like nitrous injecting cooled liquid into the cumbustion chamber creates more power.

I dont know the exact science but its somewhat obvious.

Answer 7

chilly air can carry greater oxygen in line with unit quantity than heat air. Your laptop measures the quantity of air going into the vehicle to settle on how lots gasoline to inject. some autos degree the oxygen in the exhaust with an oxygen sensor and a few autos degree the oxygen entering on the intake.

Answer 8

The parts fit tighter better compression better combustion,cooler air improves combustion also.

Answer 9

Because of Latent vapouration.

Answer 10

dont think thats true when its cold outside you have to let your car warm before you can drive it or you will ruin your engine