How much does wind effect fuel economy?

Discussion in 'Fuel Economy' started by MT bucket, Jun 21, 2008.

  1. MT bucket

    MT bucket I want my MPG!

    I know this sounds like a stupid question, but I have not thought about this too much even though I have driven over a million miles.
    How much does driving into the wind effect fuel economy?
    Here is the thing that brought this to mind.
    I am driving my 91 colt and I had to make a run from Minneapolis to winona, on the way down I crossed over to wisconsin at prescott off of hwy 61 to avoind the long backup at the hastings bridge that is being repaired. I got on wis. 35 to cross over at wabasha, then back on us 61 the rest of the way.
    I did not notice any wind. 35 was nice and smoth pavement but really hilly and curvy.
    I coasted out of gear on the down hills to try to make up for the extra gas needed to get up the hills. All coasting was with the engine on, not ready for the engine off stuff yet.
    I drove 50 to 55 most of the way ecept for slowdowns thru towns.
    I got to Winona and stopped to fill up, I found I got the best mileage I have ever had, 50.27 miles per gallon!
    On the way back I decided to stay on 61 up to hasting and then take hwy 55 home, it was alot flatter so I thought I would do even better.
    Well, first thing I noticed was the road was quite a bit rougher, I wondered if that was a negative, then when I got past wabasha a big north wind came up to drive into. I noticed when I got past lake city there were big waves on some tiny lakes!
    I wondered if it would have any effect but was still expecting good numbers.
    I got close to home and topped off, and couldn't believe how much gas I used!
    I ended up only getting 38 mpg! still better than what my car is rated for, but 12 lower was unexpected! The only thing I could come up with with was it was driving into that wind for a good portion of the time, I drove the same speed, everything else was the same except it was less curvy and much milder hills.

    Any suggestions ?
  2. HemiSync

    HemiSync Well-Known Member

  3. MT bucket

    MT bucket I want my MPG!

    Interesting disscussion, thanks.
    So is my experience with the wind yesterday pretty normal?
    Is driving into a 25 mph wind at 55 pretty much the same as driving 80 with no wind?
  4. Big Dave

    Big Dave Well-Known Member

    Pilots have a saying: Any wind more than thirty degrees off the tail is a headwind.
  5. donee

    donee Well-Known Member

    Hi MT... ,

    That is right. 25 + 55 is an 80 mph airspeed.

    But its not exactly the same as driving 80 mph on a calm day. Because the engine will be operating at a 55 mph RPM, but a 80 mph power. Engines are usually more efficient at the higher torque of the head wind driving.

    BTW, a friend of my youngest brother had one of those Mitsubishi balance-shaft Colts. Quite a smooth engine for a 4 banger. They drove it to Florida for Golf Pro school. The day they were to leave they found out the front brakes were toast. So, I did a quicky pad job for them. One ended up a Golf Pro, not that brother however. Another brother did become a golf pro however.
  6. Jan

    Jan New Member

    I tend to think that wind averages to zero when driving around. However, this doesn't account for the drag :) See an explanation here.
  7. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I don't think I will click on your link, Jan.
  8. Jan

    Jan New Member

    Ok, then don't do so.
  9. ALS

    ALS Super Moderator Staff Member

    Edwin, it's a safe link unless you're afraid of Physics equations. :p
  10. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Sorry , Jan. We've had a lot of spam-merchants cruising our site. When someone signs up as a member , then posts something with a link on his first day , I'm suspicious.
    BillLin likes this.

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