Better gas mileage

[okccj]

Better fuel economy. A/C on with windows up, or A/C off windows down?

 

[boscounderfoot]

Mythbusters

Better fuel economy. A/C on with windows up, or A/C off windows down?

The crew on Mythbusters did a thorough test of this very subject and found no real difference between the two.

 

[bosmob]

I have a 2nd Gen V6 Auto and this is what I have found out:

A/C Compressor ON Windows UP: 190-200 miles per tank.
A/C Compressor OFF Windows Down: 240-250 miles per tank.

 

[ChoochCharlie]

Yep. Windows are about 40 miles better than A/C per tank for me too.

 

[fishrod]

Without any numbers to back my answer up I would still say windows down, AC off by a country mile.

What car were mythbusters driving when they tested this? A big 6lt diesel GM/ford/dodge truck where the compressor wouldnt really affect the engine that much?

 

[Nodd]

I believe the Mythbusters noted that if you're driving at highway speeds then windows up/AC on = better MPG. Around town or on the trail then windows down/AC off = better. Basically the wind drag from the open windows isn't a factor unless you're really moving.

 

[fishrod]

Hmm, so Mythbusters used a big ford expedition or something in their test.

Their first test (only 5 laps of a race track) using a computer air meter, showed that the AC on, windows up was more efficient (only just). This was at 55mph.

The second test they filled two identical cars up and drove until the tanks went dry. This was done at 45mph and the Windows Down AC off lasted 30 laps longer.

I would think the air compressor wouldnt affect the engine much on a big 5lt engine as opposed to our little 3lt engines. Also the bigger truck with all the windows down probably attracts more drag than our smaller truck does.

 

[bosmob]

I believe the Mythbusters noted that if you're driving at highway speeds then windows up/AC on = better MPG. Around town or on the trail then windows down/AC off = better. Basically the wind drag from the open windows isn't a factor unless you're really moving.

When I open my driver's side window, I usually open the rear driver's side window also. It keeps the whipping of the air down and reduces drag because the air has somewhere to go after it enters the cabin.

 

[fishrod]

I like opening the sunroof, driver and front passenger and the back window to get lots of air flowing!! 8)

 

[bosmob]

I like opening the sunroof, driver and front passenger and the back window to get lots of air flowing!! 8)

haha! I sometimes do that too but it just takes to long to open everything... :bigok:

 

[Nodd]

I have a bloody great spare tire on my roof so window drag is the least of my problems. Besides my 3.slo crawls to a near halt in protest if I go anywhere near the AC button. Lets just say its not exactly running like new. Windows down works for me

 

[shortyboy192]

I think vehicles that are this is tested on don't have a rear window that rolls down. With the rear window all the way down I think 4runners become more aerodynamic than other vehicles with the windows down.

 

[Maritimer]

Sunroof open and rear window down, no air conditioning. Now it's starting to get cold enough that I use the heater in the mornings anyway. It's nice to run the A/C every couple of weeks just to keep it in order, though.

My question is about turning the window defog or defrost on. When the air is blowing on the windshield in my CR-V the A/C light comes on automatically. The Runner doesn't do this, but the A/C drain tube spurts out the water really well. I assume the A/C is running then? Also, does anyone know the best way to get this not to dump water on my frame? That part of the frame of course seems rusty compared to other parts.

 

[RAYnoodle]

i roll both front windows and tailgate window down.

 

[90toytruck.]

front windows down tailgate window down as well good flow !