dilkie's Forum Comments
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fuel economy question
Lots of reasons:
- Higher wind resistance
o Cold air is more dense, a 70F drop in air temp yields 10% more dense air
o Costs more power to move the same speed on the hiway.
- Higher rolling resistance in the cold
o More viscous lubricants, transmission, bearings, engine oil
o lasts until lubs get up to temperature. (wheel bearing and diff never does, tranny takes a long time)
o Tires deflate some in the cold, check tire pressure when temp goes down.
o Tires get harder in the cold, more rolling resistance.
o If you change to winter tires, they also have more rolling resistance then summer tires.
- Engine efficiency goes down.
o Fuel doesn't vaporize as well in a cold engine. Remember, fuel is exposed to outside air temp always.
o Denser air, due to cold, actually can yield a bit more power but that generally yields less efficiency. (not really sure how much effect this has)
posted by dilkie December 22, 2009 at 6:14 AM