Its about the WORST thing for gas mileage....

I was crusing home, had just filled my tank, so I was up to about 56 mpg, and there is a Wind Advisory here in La Verne, so as I'm getting home, a BIG wind picks up, and I have to fight through it for about 13 miles to get home. When I arrive, my mpg is 49.4

 

Yeah, we got 'dem bad ol' Santa Ana winds here in Southern California. My commute to work is heading into the wind, and is on a slight incline. Ordinarily, I get mid-40's, but today's trip was 36mpg. Hopefully make up for it going home with the tailwind.

Don

 

I did some searches on wind resistance and aerodynamic drag. This was the most interesting result:

http://auto.howstuffworks.com/question477.htm

I'd summarize the equation (in words), as the power required to move your car is equal to (rolling resistance/friction * velocity) + (RR/friction/energy to run pumps and such * velocity squared) + (aerodynamic drag * velocity cubed).

Not being a physicists or mechanical engineer I have to take the equation at face value. so if it's true, velocity and drag are the biggest offenders at highter speeds. The article points out that at around 40 mph, rolling resistance and friction give way to drag as being the primary force to overcome, noting that in very general terms the 'sweet spot' is around 40-60 mph. Something most of us know through experience anyway. So if you had that headwind, it's going to be compounded by your speed. Seems like the only way to offset it would be to slow down, if possible.

 

I was doing 60 most of the way as I also recognized the need to slow down. The winds were gusting quite high -- the radio said up to 75mph, but all I noticed was that I needed both hands on the wheel to prevent impromptu lane changes during gusts. That being said, even 30 mph gusts in my face would seem like 90mph to the car, eh?

Don
'

 

yea, the effect of the wind is even worse for me as i drive my box on wheels... only a few more weeks til my hch arrives!!!

 

A couple of weeks ago a cold front blew through during the night. That morning I had to drive home from work into the teeth of winds gusting to 40 mph. The combination of wind & cold knocked >2 mpg off the meter.

 

Every place I've looked shows aerodynamic drag as proportional to the square of velocity.
http://www.windpower.org/en/tour/wtrb/drag.htm
http://www.insideracingtechnology.com/tech102drag.htm
etc.

 

That is true for the drag (the force exerted by the air), but he was talking about the energy required to oppose that force in relation to the other energies consumed by the car while in motion.

~Droid

 

Basic Newtonian physics - to maintain constant motion, any force must be countered by an equal force in the opposite direction. If air drag is proportional to the square of velocity then the force required to overcome drag is proportional to the square of velocity.

 

How about wind and rain?

Even worse, an iced road?