Windows Down = bad mpg?

[95xeb]

I read a post on here that mentioned somethign about windows down causing bad gas mileage... why is this? Someone said that they got better mpg with windows up and AC ON... I've got an eddie bauer, so i'm constantly watching the mileage on the computer... Recently my mileage dropped TERRIBLY. It's a 95 with just over 80k. I cant get anything better than 9 mpg in town. I noticed it about 3 tanks ago, and have been very conscious to drive "nice" since. As best as I can tell, it's got nothing to do with my driving habits. This last tank that I'm on I added fuel injector cleaner to. I've heard the cleaner can reak havok on o2's... is this correct? What else can I try? Oh, I forgot to mention, I'm in Melbourne, FL, so I always drive with no ac, windows down, and sunroof open. Any help is greatly appreciated... I'm a broke college student and its costing me a fortune to drive.

 

[Rick]

Driving with the windows down disrupts the airflow around the vehicle. That screws up the aerodynamics the engineers work so hard to engineer into the vehicles.

If you're getting 9mpg you have some serious problems and it's not from the windows being rolled down.

 

[Jason_25]

Could be a fuel pressure regulator problem if it was a drastic drop in mileage. You may want to check and see if the fuel system is within specs.

 

[Majisto]

Heh I posted about the mileage deal with windows up and AC on. Don't really listen to me because the gas gauge in the Explorer is the most pitiful excuse for a guage I have seen this side of the Camaro I would drive with the windows up and the vent on if you don't want to use the AC.

 

[Robert]

The affect of lower MPG with the windows down only comes into play at highway speeds. Around town, you will get better mileage with the windows down and the A/C off. It's only once aerodynamics come in to play that the windows have an affect. Here in Arizona I spend a great deal of my drives with the windows down (both around town and on the highway). I have tracked my mileage with every tank of gas I have put in my Explorer since I bought it new in July, 1997. I can see no noticeable affects to my mileage during the times of year that I regularly drive with my windows down. This is one of those times of year (86 yesterday). As Rick said, if you are only getting 9 MPG, then there is something wrong that has nothing to do with your windows.

 

[scratched 95]

Originally posted by Rick
Driving with the windows down disrupts the airflow around the vehicle. That screws up the aerodynamics the engineers work so hard to engineer into the vehicles.

The Explorer is nothing but a big box. The only way you are going to affect the (lack of) aerodynamics is to open the winshield!

 

[JDraper]

Originally posted by scratched 95
The Explorer is nothing but a big box. The only way you are going to affect the (lack of) aerodynamics is to open the winshield!

You're right that the Explorer has the aerodynamics of a brick, but you would be suprised at how much a difference opening the windows will make. Even though the X has a large frontal area, the drag down the sides is a large part of the equation. Opening the windows will cause a significant change in the drag. You know what it feels like to put your hand out the window at 55 MPH, now imagine your hand being 2' tall and the force that would be on it. That's the kind of drag the rear of the window frame will add when the window is down. Why do you think the boys at NASCAR plexed in the driver's side window? Wasn't for comfort, it was to reduce drag. At highway speed you will probably drop several MPG with the windows open. Although getting only 9MPG is something way more than open windows.

 

[Xplodor]

I'm getting around 10mpg right now. It's split between highway driving, city driving, and just plain sitting in 2 hours of freeway traffic a day. I have however lifted my truck, have the heavy rockcrawling rims, 33" tires x 12.5" wide, and drive with my windows down. When I drove to TruckHaven this last week my milage went up close to stock, I was carrying a consistant speed and had the windows up most of th time. I still have my stock 4.10 gears in, so I'm just thinking that it's the stop and go traffic that is causing me my heartache with the 33s and heavier rims. Good Luck, might want to get it checked out.

 

[JDraper]

Hey Xplodor, did you re-program the computer to take into account the change in tire size?? If not, and you don't alter your fuel mileage equation, you are probably getting better mileage than you think.

 

[woodychitwn]

Originally posted by Xplodor
I'm getting around 10mpg right now.

Um, so that's bad, huh? Just of curiosity and assuming that Xplodor is adjusting his calculations for the larger tire size, what could cause that kind of fuel economy? This summer, I think I was getting 8mpg, and otherwise it's about 12mpg. The truck does have over 200,000 miles, so that might weigh in.

 

[JDraper]

Could be a bunch of things, but you ought to be getting better mileage than that! Dirty MAF sensor, bad o2 sensor, dirty injectors, worn rings and worn plugs can all contribute to that. When I had a '92 Sport 4x4 with a 5 speed(stock except for a Flowie cat back exhaust), I was getting about 19-23 MPG, and I'm not easy on the gas by any stretch of the imagination.

 

[Xplodor]

It has not been recalibrated, but I've check with my GPS and check how off the speedo is with the GPS and a friends vehicle riding side by side. It's still around that low. Again, I think regearing, custom chip programming to adjust for gear, tires, preformance, and going to alum. wheels will bring me back to a happy MPG.

 

[VOATMJ1]

I agree with JDraper, I get (according to my hand held computer), 25 MPG highway, and 18.5 city, I don't floor it from light to light, but I'm no slow poke either.

If your only getting 9 MPG, I would head for the nearest shop, you definitely have a problem!

Maybe a clogged fuel filter, bad sensor making the engine run rich, or something. 9 MPG is about what late model 18 wheelers get pulling a load!

Have it checked!

 

[Alec]

9 MPG is about what I get in the city with very very very hard driving. And I have 2x the power as your motor (and thus am dumping twice the fuel into it)!

9 mpg is bad for most vehicles.

 

[DesertSpive]

Feeling alot better about my 15mpg city now. 9 or 10 is really just unacceptable. I am running a 4.0L SOHC/stick with 4.10s and 33x12.5s. I don't know what I would do with 10mpg.

--Sean

 

[Majisto]

Originally posted by DesertSpive
Feeling alot better about my 15mpg city now. 9 or 10 is really just unacceptable. I am running a 4.0L SOHC/stick with 4.10s and 33x12.5s. I don't know what I would do with 10mpg.

--Sean

Huh?! Since when do SOHCs have manuals?

 

[Mike]

i get 11.5-12 mpg on my v8.. =[

 

[Alec]

SOHCs had the manual option '01+. He also has a Ranger, where sticks are more common.

 

[Majisto]

Originally posted by Alec
SOHCs had the manual option '01+. He also has a Ranger, where sticks are more common.

Hrm...interesting. When it's trade-in time I think I know what i'm getting then

 

[DesertSpive]

Yeah, I am talking about the Ranger.

--Sean