Wondering why people complain that Yaris' cant get good mileage?!

[BailOut]

Originally Posted by yarrr

On the freeway, having windows down creates drag which hurts your FE than having the A/C on.

This is inaccurate. In both testing with our SGII's and as proven in the 3rd season of the Mythbusters television show, windows down is always more efficient than a/c at any speed.

In fact, with the SGII it is nigh impossible to read the drag hit of having the windows down, but turning on the a/c at any speed is an instant large and sustained hit to FE.

[daf62757]

Originally Posted by BailOut

This is inaccurate. In both testing with our SGII's and as proven in the 3rd season of the Mythbusters television show, windows down is always more efficient than a/c at any speed.

In fact, with the SGII it is nigh impossible to read the drag hit of having the windows down, but turning on the a/c at any speed is an instant large and sustained hit to FE.

I didn't see that episode, but I did a search on found this website.

http://green.autoblog.com/2007/08/29...-down-episode/

According to the website, windows down does hurt mileage. Just on a simple physics level, the air entering the cabin has to have some breaking action on the vehicle as the air has no place to displace. If you had the tail open, it could be a flow through action that might not effect the velocity of the car.

I am no expert on the matter....but I did stay at a Holiday Inn Express last night and will use my AC....because I love cold air and I am rich enough to afford the extra quarter.

[Yarisduder]

Originally Posted by BailOut

In fact, with the SGII it is nigh impossible to read the drag hit of having the windows down, but turning on the a/c at any speed is an instant large and sustained hit to FE.

Do you have numbers to share with us? How did you control your environment? Was the ground flat? What speeds, was there wind, etc?


-

[BailOut]

Originally Posted by Yarisduder

Do you have numbers to share with us? How did you control your environment? Was the ground flat? What speeds, was there wind, etc?

There was a big thread on it that was lost in the hack, but as I said the Mythbusters found the same thing, as did the folks on CleanMPG, as did the folks on PriusChat, etc. In other words it has become common knowledge.

As for the test environment, etc., it simply doesn't matter. Windows down in any scenario is far, far more efficient than using a/c in any scenario. It doesn't matter if you're pulling into your driveway or cruising down a highway, rain or shine, winds or no.

Tinting goes a long way for avoiding a/c use. When combined with window vents it lets me keep the 35% front window on the sunny side cracked about 2 inches and have the shaded window fully down, or both windows down when the sun is directly overhead or to the front. Aided by the 6% tint on the rear windows and top of the windshield (the darkest allowed by local laws) it helps keep the interior much cooler than without any of these things. In stifling heat I run the fan (just the fan - no a/c) on the fresh intake setting to aid with circulation.

Despite living in a high desert region the only times I have ever run the a/c is when my wife experiences hormonal issues. None of my other passengers ever ask for it.

[docB]

When myth busters ran the A/C vs windows down show...shame on them. They used Ford Exploders or something larger. They get the same mpg no mater what the condintions. Read terrible. If they used a genuine fuel efficient vehicle they would have had a better test. I had a 1989 Subaru Justy w/ a CVT. If the tire pressures dropped a few, I lost MPG. I got high 49 mpg on a road trip once. A pluged air filter showed a few mpg loss. The Yaris is such a vehicle. I do not use Scan Gauge. I have kept a log of all the gas through the thing since I got it. Overall to date is 39.8 iirc. High single tank is over 44.
doc

[krolos]

The Ac efficiency on the Yaris really impresses me, I have compared my mpg
with it on or off,and I can Say that I have seen very little difference if any at all, compared to other cars I have owned in the past this is big Improvement.
On the Interstate highway With Ac on and roof rack and surfboard {9 1/2 foot longboard}
averging 73-76 mph I still easily get 37/38 mpg I am quite happy with that.

[yarrr]

Originally Posted by BailOut

This is inaccurate. In both testing with our SGII's and as proven in the 3rd season of the Mythbusters television show, windows down is always more efficient than a/c at any speed.

In fact, with the SGII it is nigh impossible to read the drag hit of having the windows down, but turning on the a/c at any speed is an instant large and sustained hit to FE.

uh.

http://en.wikipedia.org/wiki/MythBusters_(2004_season)

Myth statement
Running a car with air conditioning on is more fuel efficient than running with the windows down.

Status
Partly Busted

Notes
Tests were performed under varying conditions (55 miles per hour (89 km/h) versus 45 miles per hour (72 km/h)). Also, the 55 mph test was using a computer to estimate fuel efficiency based on air intake, not actual fuel consumption, and showed A/C was more efficient. The 45 mph test consisted of running the tank until it was empty, and showed open windows were more efficient. This experiment—or one like it—is sometimes cited by the Magliozzi Brothers on Car Talk when presented with this question.


http://en.wikipedia.org/wiki/MythBusters_(2005_season)

Myth statement
Running a car with air conditioning on is more fuel efficient than running with the windows down. (From AC vs. Windows Down)

Status
Partly Re-Busted/Partly Confirmed

Notes
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 the windows down, but going greater than 50mph it is more efficient to use the A/C.



The sad thing is I just pull stuff out of my ass most of the time, you write novels on this crap.

[KrazyDawg]

Originally Posted by BailOut

In fact, with the SGII it is nigh impossible to read the drag hit of having the windows down, but turning on the a/c at any speed is an instant large and sustained hit to FE.

That's good to know. I always thought 40-45 MPH was the breaking point between having the A/C and window open but I found out I was actually getting higher MPG on one fill-up with the windows open and 90ºF weather.

Does it make a difference if only the driver side window is open? I don't have power windows.

How much of a MPG hit do you take going from A/C level I to level II? What about when you compare no air to air on level II but with A/C off?