A/C in car Vs. using the vent

[Dsunny1]

I live in Michigan, so we don't need A/C in the car yet, but I do wonder what the compairison is between using it or just the vent air when I am on the highway. I usually roll down the windows when I am going less then 45 or so. Does anyone know if using the "vent" option save you much over actually turning on the A/C, or is it really the same thing, just not as cold?
Thanks
Jen

[ukbb]

The Myth Busters looked into this

http://mythbustersresults.com/episode38

REVISITED: Running a car with air conditioning on is more fuel efficient than running with the windows down. (From episode 22)

partly confirmed

The fundamental flaw in the MythBusters’ test was that the point where the drag becomes powerful enough to inhibit a car’s performance with windows down was inside their 45 - 55mph margin at 50mph. Going less than 50mph it is more efficient to leave your windows down, but going greater than 50mph it is more efficient to use your A/C.

[C@rol]

Great queston.
Good to know that. I'll keep it in mind this summer.

[mombottoo]

Since using the vent option isn't the same as having your windows rolled down I would think the vent option would save you money when you are on the highway.

I live in Michigan too! Luckily we don't get many days that require a/c in the car.

[ukbb]

I live in Michigan too! Luckily we don't get many days that require a/c in the car.

I'm in MI too. I drive a black car with a dark interior. I get plenty of opportunity to use my a/c.