Turned on a/c, dropped 6 mpg

[CROWNVIC4LIFE]

There is zero difference in all our Panthers [power-wise] so we just leave it on automatic all the time all year long...I really do not know the difference in gas mileage cause we never shut it off but we do get overall good mileage...I just got 26 mpg [highway] on a long trip recently.

I really can not figure out why anyone would want to drive at 75-80 mph with their windows down no matter what the temperature is outside.

 

[ryansride2017]

Originally Posted By: mpvue
Originally Posted By: ryansride2017
That's one mythbusters show I never agreed with. Their conclusions were that running above 45-50 mph, wind resistance with the windows open consumes more gasoline than using the air conditioner. I just don't see it in the real world.

sooo, 2 guys that used the scientific method to come to a conclusion with data to back up their findings, you have decided not to agree with.
okay, makes perfect sense.


Noooooo, based upon my years of driving multiple vehicles (not just one or two like in the television show - real scientific) and gas receipts. I've conducted my own scientific method of observing fuel economy consisting of thousands of fill-ups.

 

[Gary Allan]

Quote:
You don't? Think how much time and money auto engineers take to make cars as aerodynamic as possible. Very tiny differences in shape and styling can make a huge impact. You don't think a couple gaping, 1 1/2' x 1 1/2' gaps might make more difference than a small compressor running off the belt?


Quote:
sooo, 2 guys that used the scientific method to come to a conclusion with data to back up their findings, you have decided not to agree with.
okay, makes perfect sense.


I would think not. At least not in all cases. The cycling of the AC compressor can physically slow the vehicle at a given output level. I don't think rolling the windows down will do the same.

The AC an assess a fairly big toll on my son's NEON. He gets about 34mph in our rolling terrain in a cool/cold weather commute. That drops to 26-28 with full time AC usage. Open windows would hardly account for that much.

 

[jorton]

Originally Posted By: Johnny
Roll the windows down and turn the A/C off. If you get hot, go down to the River Walk and have a cold one at one of the fine establishments.


On the way home from work I'm driving in to a headwind almost every day. With the a/c on the car shifts down on overpasses. At least with this car I can leave the windows down in the parking lot at work.

 

[meep]

keep in mind that vehicle A/C must be sized to drop cabin temps quickly when getting in a baking car. My 01 T&C had the same tonnage as a 1,500 sq ft house, IIRC.

So that little saturn, if they followed the math, needed the equivalent of an efficiency apartment... 400-500 sq ft room.

Once the car is cool and the compressor cycles instead of locked on, energy used is less. So, 20 minute commutes will be a much larger mpg hit than a 6 hr drive...

Mike

 

[mechtech2]

Mythbusters is often just plain wrong.
Like running through rain for a given distance makes you wetter than walking through it.
And their childish thinking concerning firearm recoil is also faulty. [they consider firing a weapon as an instant explosion, not a 'slow' burn with spread out recoil, when comparing it to the impact of the bullet ]
I quit watching them a long time ago. Every test is fun, but mostly for the show.

 

[swalve]

When my systems are low on charge, I can feel them lugging against the engine more. Maybe low on refrigerant?

 

[mjoekingz28]

In my Saturn, which doesn't have a clutch-the compressor is on all the time, I dropped down to 33mpg from 40 and that is 90% highway at 65mph.

Also, whether the windows are all the way up, halfway, or fully open hasn't changed my mpg any(by a single mpg or more at least).