Do rain guards effect MPG?

Has anyone installed rain guards and seen a difference in MPG(I am guessing a decrees)? I want to get them so I can always leave the windows down about an inch or two...

I have them on my gen2 and have recorded no mpg drop. I suppose technically they add to wind resistance and obviously they weigh something but the difference must be very small.

That is EXACTLY what i wanted to hear Do you have any pictures of them on? I am curious to see how it looks

I do not have pictures at the moment and it's dark here (late evening) but as soon as I can take a picture I will post.

My mpg is 64.8mpg (UK gallons) with 205/55/16 tyres.

John.

Sounds good! Thanks John

Pictures as requested. View attachment 40765 View attachment 40765

Sorry only one picture appeared the other is hear.

See here
WeatherTech window deflector install tips with diagrams | PriusChat
for my install process and some pictures.
Good luck!

they look good 2009prius! Does anyone have the type that go on the door?

mine does.. doesn't affect mpg at all at moderate speeds. at highway speeds, where i can feel a slight breeze inside, it might have that minimal effect.

Let's take this back to high school physics.

I suppose your concern about MPG reduction comes from the idea that anything sticking off the car will increase the drag force, hence making the engine work harder to maintain the same speed.

The formula that determines drag force is linearly proportional to the frontal area of the vehicle. That is to say, with each increase of area, there is a directly proportional increase in the drag force. 1% more area, 1% more drag.

So what percentage of the Prius's frontal area is going to be rain guards? The Prius's frontal area is about 28 sq ft (within a few percent). I'm going to guess these rain guards stick out all of an inch, and have a couple feet of frontal height (height as viewed from the front). That's going to add... 1/3 of a sq ft, or 1% more frontal area.

1% more frontal area. 1% more drag. Do you really need to worry about 1% more drag? I'd say forget about it.

Hi They look really sharp yet, what is the purpose ?? will having the windows cracked on COOL days keep the main batterys cool enough so as not to worry ME + shorten their lifespan ??
1 more thing---I have a realy big question-where does one post NEW ?'s after having SEARCHED for a possible previous listing. Thanks, DJ

Maestro8 and AgentJ Thank you very much

Click on the "Post New Thread" buttons found on the right hand side of page towards the top and bottom of each subforum. Take a look here: Gen II Prius Main Forum | PriusChat

THANK YOU--Since I turned 39 (again), my 4-eyes tend to miss a lot of things...unless they have large headlights. Lol