Ever wondered how much fuel economy loss happens when windows are open in your car?
No related posts.
Fuel Economy Test #3: can opened windows kill fuel economy?
Previous post: SEE WHAT’S NEW In Fuel Economy Technology!!
Next post: Ford finds EcoDriving can improve fuel economy by 24% on avg
{ 25 comments… read them below or add one }
Yup, folding the mirrors will do the trick. I actually did another test video where I got rid of my exterior mirrors entirely (and just had one big interior mirror) and it saved more than 2% in fuel economy.
So if there are no cars on the highway, should I fold in the side mirrors to boost fuel economy?
Km/h is what my original car’s speedometer reads. The ScanGauge electronic device on the dash was calibrated to measure gallons consumed/hour and miles travelled per hour.
I like using the miles/gallon equation because it’s the standard that Americans (and a sizable amount of the Canadian population) use when measuring fuel consumption.
Sorry, my math is off a bit. I stand corrected.
You mentioned KPH for your speed. How did you arrive at the MPG number?
I removed the mirror to increase fuel economy. 80-km/h works out to be around 50-mph, so that’s why the fuel economy is so great. The faster I go, the more air the car has to push. At 70-mph, the Geo only gets a meager 37-mpg.
Are you SURE about your numbers?
You said 80KPH, but when you calculated fuel economy, you said MPG.
80KPH is somewhere around 40MPH (roughly), and 100KPH is about 55MPH.
Try your test in the summertime, but then add the use of A/C to see any difference.
Also, did you remove the PS mirror? That too can skew the results.
Let me know when you complete the test. I’d be interested in seeing the video
I also did the hatchback test in my test #2 “the importance or aerodynamics”.
I’m going to be running a simular test with all 4 windows open, and the rear hatch open vs. closed on my Vibe. I assume the hatch being opened will help air flow but the hatch sticks up above the roofline increasing drag.
Yeah, I sure do. I actually bought my first bike (used of course for $40) at the end of January and started riding it immediately after. When dressed appropriately cold temperatures aren’t that bad. The only thing I’d change for next year is that I’ll invest in a snow-mobile helmet with a visor to keep my face warm.
ohh good point u rid ur bike in winter???
Nope. I’m just saying that my old car today would cost 25 cents in fuel for ever mile I drive. So now that I’m riding my bike, I’m saving that amount every mile I travel with it (for example: I’ve now gone 263 miles on my bike within 1 month. So I could pay myself $66 since that’s the amount of fuel I saved).
do you add acetone to your bike??
It was totaled in a collision last March. Insurance paid me $1,690 for it. Now I’m riding a bicycle because gas in Canada here is now heading towards $6.00 a gallon. Every mile I travel on bike is like paying myself 25 cents in fuel alone.
ill buy that car from you!!!
gimme a price!
i get 14.1mpg in my car :’(
yeah, I never use A/C anyways. I need fresh air even if it’s 90F out.
At only 1.8% reduction in fuel economy @ 50-mph, I bet it’s much better having windows down compared to A/C on
It would only be like paying 6 cents a gallon more for fuel (if fuel is $3.50 a gallon).
Well, usually when I have the window open, my elbow is resting on the door, so I imagine my exposed elbow is dragging me down and costing me money. Stupid elbow…
Your English is great.
Yeah, 80-km/h only works if you live in a place like Winnipeg Canada. The highest speed limit currently in this country is 110-km/h, so testing at that speed would make more of an impact I’m sure.
Maybe driving the vehicle at 100 km/h or whatever the maximum speed limit on the motorway is in you country. You would find you get difference results. No one really drives around at 80 km/h on the motorway, too slow. Sorry if my English is bad.
I only drove about 40 kilometres during the experiment which is only like 2 litres of fuel. The weight difference is pretty small.
remember that your car went lighter because you used up some gas. Therefore, a lighter car will increase your MPG.
No such thing as a economy car no matter how car technology has progress .for the simple reason cars spend most of their time stuck in town and city traffic plus slow moving traffic on the roads. Therefore all cars are doing fuck all MPG. Excluding electric the only vehicles on the road that have good fuel economy are motorbikes because they don’t be stuck in slow moving traffic wasting fuel out of the exhaust..
I guess you should redo this test using 100km/h (something about 60mph) because the drag is directly proporcional to the square of the speed, in english, more speed=more drag=more precise measure
If you would i’d like ^^
Thanks
I’ll have to watch that episode, as people say it was a good one.
Mythbusters did a segment on this same question. I don’t remember the test vehicles used, but windows down was 15% more efficient than using A/C.
Putting a drag on the engine with an A/C compressor is definitely worse than any ‘drag’ from disrupting the areodynamics.
Of course, no two cars are alike so their design may play a significant role.