Originally Posted by CR94
At low speeds, windows up always uses less fuel, ...
I meant "down" there; sorry for the muddlement.
At low speeds, windows up always uses less fuel, ...
I meant "down" there; sorry for the muddlement.
Is there now a consensus on AC On vs Windows Down to save MPG
- Thread starter Speak2Mountain
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Originally Posted by DriveHard
In my Fiat 500, turning on the AC will drop MPG by 5-7 at 65 mph.
1. Because the compressor is bigger than the engine
2. Aerodynamics of a toaster
In my Fiat 500, turning on the AC will drop MPG by 5-7 at 65 mph.
1. Because the compressor is bigger than the engine
2. Aerodynamics of a toaster
Originally Posted by 4WD
Originally Posted by DriveHard
In my Fiat 500, turning on the AC will drop MPG by 5-7 at 65 mph.
1. Because the compressor is bigger than the engine
2. Aerodynamics of a toaster
Originally Posted by DriveHard
In my Fiat 500, turning on the AC will drop MPG by 5-7 at 65 mph.
1. Because the compressor is bigger than the engine
2. Aerodynamics of a toaster
Originally Posted by shadow7
What about the wind noise while driving with the windows open on the hwy? Wind noise hurts my ears
Yep, gets real old real quick. I'd rather be comfortable than chase a few relatively meaningless MPG's.
What about the wind noise while driving with the windows open on the hwy? Wind noise hurts my ears
Yep, gets real old real quick. I'd rather be comfortable than chase a few relatively meaningless MPG's.
Originally Posted by DBMaster
I still remember my buddy's 68 Firebird from high school. It had no AC and a black vinyl interior. Needless to say, in the summer we always rode in my 72 Catalina with the Frigidaire "freeze you out" compressor.
My 77 Caprice would have cooled off a 7 room house.
The only time I drop a window is for a parking garage. I set it and forget it [between 68-72] the entire time I own it no matter what the temperature is outside. Keeps the interior a lot cleaner.
I still remember my buddy's 68 Firebird from high school. It had no AC and a black vinyl interior. Needless to say, in the summer we always rode in my 72 Catalina with the Frigidaire "freeze you out" compressor.
My 77 Caprice would have cooled off a 7 room house.
The only time I drop a window is for a parking garage. I set it and forget it [between 68-72] the entire time I own it no matter what the temperature is outside. Keeps the interior a lot cleaner.
Aerodynamics is not linear proportional to speed. At highway speed (I think around 50mph) AC always use less fuel than opening the windows.
Originally Posted by Tahoe4Life
Originally Posted by DBMaster
I still remember my buddy's 68 Firebird from high school. It had no AC and a black vinyl interior. Needless to say, in the summer we always rode in my 72 Catalina with the Frigidaire "freeze you out" compressor.
My 77 Caprice would have cooled off a 7 room house.
The only time I drop a window is for a parking garage. I set it and forget it [between 68-72] the entire time I own it no matter what the temperature is outside. Keeps the interior a lot cleaner.
Cleaner interior, definitely!
Originally Posted by DBMaster
I still remember my buddy's 68 Firebird from high school. It had no AC and a black vinyl interior. Needless to say, in the summer we always rode in my 72 Catalina with the Frigidaire "freeze you out" compressor.
My 77 Caprice would have cooled off a 7 room house.
The only time I drop a window is for a parking garage. I set it and forget it [between 68-72] the entire time I own it no matter what the temperature is outside. Keeps the interior a lot cleaner.
Cleaner interior, definitely!
Amusing that most replies ignore the title question.
Silly roll down windows to save gas when never ever been cheaper(adjusted for inflation).
Do what you prefer.
Do what you prefer.
The flip side of my prior post about how much duty cycle the A/C system would have (for similar comfort to the windows down) is, how far down would you put the window since it can have a variable affect on drag?
Often in spring and fall, I'll crack the window, the amount depending on the speed I'm going. It's just nice to feel a breeze even if I don't need cooled by it.
In spring it is also nice to push a bunch of air through the vehicle to help dry out any moisture that my feet, wet from rain, put in it.
Often in spring and fall, I'll crack the window, the amount depending on the speed I'm going. It's just nice to feel a breeze even if I don't need cooled by it.
In spring it is also nice to push a bunch of air through the vehicle to help dry out any moisture that my feet, wet from rain, put in it.
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The type of vehicle & engine combination makes a huge difference. A very lightweight car with a small engine and high wind profile (EX: Kia Soul, Nissan Versa) would really suffer with the windows down. A heavy car with large engine and low profile (Corvette, Mercedes-Benz, C-Class) would hardly notice the wind drag.
My anecdata:
1994 F-150: Better mileage with the windows closed. The AC doesn't work, but setting the HVAC to vent cools things down acceptably in about 70 degree ambient. Warmer than that, roll down the windows, open the wing windows and the rear slider, cools down in a hurry while moving. The added aerodynamic drag certainly shows up, dropping mpg by 2 or 3.
2002 Focus wagon: Better mileage with AC on, and recirculating. The AC seemed kinda weak, and I kept it on recirculating to have some sort of effectiveness. Wagon had more interior area than the rest, and probably not much in the way of insulation.
2003 Windstar: Only the 2 front door windows and the rear quarter windows open, the rear quarter windows don't open very far. So AC is required. Still gets around 20 mpg highway.
1994 F-150: Better mileage with the windows closed. The AC doesn't work, but setting the HVAC to vent cools things down acceptably in about 70 degree ambient. Warmer than that, roll down the windows, open the wing windows and the rear slider, cools down in a hurry while moving. The added aerodynamic drag certainly shows up, dropping mpg by 2 or 3.
2002 Focus wagon: Better mileage with AC on, and recirculating. The AC seemed kinda weak, and I kept it on recirculating to have some sort of effectiveness. Wagon had more interior area than the rest, and probably not much in the way of insulation.
2003 Windstar: Only the 2 front door windows and the rear quarter windows open, the rear quarter windows don't open very far. So AC is required. Still gets around 20 mpg highway.
In my '91 D21, the AC hogs ~10% more fuel than having the windows down. In my '02 Tahoe and '12 Mustang, it's the opposite.
In my 1.0L focus A/C uses an average of 3mpg than windows down. In extreme heat or humidity, the loss of fuel economy is totally worth it - except that having 1L mixed with a 6-spd manual trans means you'll be waiting forever for the engine to wind up to a respectable speed.
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