Effect of Wind on Fuel Economy

Ive noticed the same on a regular 50 mile trip that I make. I too have put it to wind. If I get in behind a large truck on the "windier" trip, the mpg will be better

 

Does this make sense?

Sure.
Why not?

 

The largest single factor in fuel efficiency is the aerodynamic drag from the air; both the result of the car's speed and the speed of the wind.

Any wind speed over about 10 MPH can have a measurable impact.

 

Yes as these are the aerodynamic effects:

• drag force - increases by the square of the velocity (i.e., what torque is required)
  
• drag power - increases by the cube of the velocity (i.e., fuel consumption)
• linear with air density - temperature being the primary driver, cold air is much denser, harder to push through
  • although a colder inlet air allows a little more engine power, our Prius has a heated manifold and the Atkinson cycle, double-passes the air through the cylinders also increasing temperature

Bob Wilson

ps. I don't know why but the title wording reminds me of a scene in the movie, Blazing Saddles. An old man, "Effect of Wind" breaks me up.

 

My smart is not aerodynamic at all. a tailwind can increase my MPG by 25%, and a headwind can reduce it by 25%. And a stiff crosswind can make lane holding a slalom event. During a recent road trip, I saw lots of Prii/Priuses and couldn't WAIT to get my hands on one... Oh, Gen IV, please hurry...

 

On a flat smooth dry road surface, on a clear and windless day at 70 degrees Fahrenheit, driving a fully warmed up Prius

At speeds under 40 mph - more than 50% of the energy used to push a Prius forward is fighting rolling resistance
At speeds over 50 mph - more than 50% of the energy used to push a Prius forward is fighting aerodynamic drag.
At about 45 mph - about 50% of the energy used to push a Prius forward is fighting rolling resistance and
the other 50% of the energy used to push a Prius forward is fighting aerodynamic drag.

 

"Push"? Front-drive cars pull themselves forward, and push themselves rearward.

 

Don't discard the temperatures

 

If the difference was only 7 mpg, then the wind wasn't all that stiff. I've seen greater differences on other cars with much lower mpg ratings.

 

Wet roads also make a surprising increase in fuel use. Wet and windy days are a perfect storm

 

On our recent trip from Ms to Az, we averaged 46.8 mpg on the way west. We mostly had cross winds there but had a tail wind home-- 50.7 mpg on the trip home. The 3,000 mile average was 48 mpg--- not bad at speeds we were running [ Texas speed limit ] So , yes, winds did factor in on our mileage. And, as Bob said above, rainy roads will hit your mpg also. As well as temps, my mpg is now above 50 since spring has sprung.