The email warning to not close the car and run the A/C right away is still making the rounds.  See: http://urbanlegends.about.com/od/automobiles/a/benzene_in_car.htm

I would like to point out in addition, that the A/C takes about 2 minutes to start pumping cold air, and it makes much more sense to drive with the windows wide open for those 2 minutes, and then to leave one of the rear windows down about 2 inches to prevent back-pressure from slowing the blower speed.  In these days of high fuel prices, this also will save money since the A/C takes power from the drivetrain, reducing what is available for accellerating into the traffic flow.  All this must be modified if you have children riding in the back of the car....

Tom

I don't know about your vehicle, but I'd venture none of the ones I normally drive take two minutes for the AC to start pumping cool air.  Now, granted it may take more than two minutes to get the car cabin cool, especially when starting from 130 degrees F.  Since I almost always use the recirculate mode, there isn't any particular back pressure from drawing in outside air.

In these days of high fuel prices, this also will save money since the A/C takes power from the drivetrain, reducing what is available for accellerating into the traffic flow. 

I might have to disagree with you on this, but it depends on the vehicle.  Some vehicles have engine control modules which monitor engine power and when the driver has the accelerator floored, the ECM automatically disengages the A/C compressor.   Even my old 1994 Ford Escort would do this function.  I can't tell you what yours does.

 

 

<<Since I almost always use the recirculate mode, there isn't any particular back pressure from drawing in outside air.>>

We stopped using recirc when we developed some sort ofungus on the inside surfaces of the AC (and we live in a dry climate, so it isn't purely environmental). The smell was very sweet to the point of being sickening. My husband had to do several treatments of Lysol. Went to fresh air intake, problem hasn't returned.

Understand.  I've not had that problem, with buildup of any kind in our A/Cs.

Re the recirculate mode, we routinely have summer temperatures in excess of 115 degrees F.  If we used the outside air for the A/C in our vehicles, we'd probably never get them cool. 

YMMV.

 

Sheldon - I'm driving a '07 Toyota Prius, and getting 55mpg mixed driving by NOT flooring the gas...  I use recirculate only if the outside air is especially dusty or smelly, like going by a papermill or dead skunk on the road.  With recirculate you can never get rid of the benzene and farts....  My 2 minute guess is from on a hot day until it is cold enuf to make a difference in the inside temp.  Yes, the A/C will drop loose during fast speed-ups, but will suck power from your engine otherwise.  My Auto A/C will cut back as the inside temp gets down to my preset temp (75).  Tom