cheap areo fix! (wash & wax your car)
 

one way to increase mpg is to wash your car and wax it. this will reduce air resistance thus increase mpgs!!!

Got any data to back that up?

Actually, I have read that several times before too.

BUT ...this comes from sources that apparently do not research the concept.

Sorry to tell you ... but it's myth.

I haven't seen you post before. Welcome to the forums !

HotRod magazine did a thing on aerodynamics at a windtunnel location, & the 'expert' that runs the windtunnel says a dirty car has the same drag as a clean car, it makes no difference

it doesn't say it here, this is the article, but the online articles tend to leave out stuff thats in the magazine

http://www.hotrod.com/techarticles/b...ips/index.html

It is true for a lear jet. A car does not go fast enough to make a difference.
The boundary layer on a car is thicker than the roughness of the dirt film.

alcivic -

I have head that this is true for airlines because they are able to save fuel doing this. I don't think it translates to cars because they don't travel fast enough. Didn't UPS have an ad where they were washing their big brown jets a long time ago?

Here is the only tangential example I could find :

Clean Drives Airline Fuel Efficiency - June 10, 2008
http://greentechnolog.com/2008/06/cl...fficiency.html
CarloSW2

I always believed the opposite.
A dirty car,(not filthy and covered in droppings) would get slightly better CdA.
Similar to the way dimples on a golf ball work.
Now somebody (not me, too lazy) is gonna hafta research.
Schultz.

Well I think Im just going just to leave well enough alone with my hood thats been rough and sun faded since I bought the car 5 years ago. :)

Speed of a golf ball:
http://findarticles.com/p/articles/m...4/ai_101967391
Faster than my driving. Tiger Woods gets up to 180 - 200.

That's the source that I was going to use.

Also, windshield angle steeper than 45 degrees is just for 'looks' It does nothing to improve the cars drag - ( that one really took me by surprise! )

Really .. wow!.. so my rear hood lift is doing nothiing besides getting the wiper out of the air flow...

I though Basjoos said his test greenhouse wind sheild canopy thing, increased his FE?

Don't believe everthing you read in Hotrod magazine...:rolleyes:

The main FE benefit of the "test greenhouse wind shield canopy thing" resulted from its rounded "A" pillars that eliminated the vortex produced by the sharp corners of the stock "A" pillars, and also since it eliminated the high pressure zone at the base of the windshield. There's nothing wrong with the angle of my stock windshield, it is just in how it was integrated into the rest of the car with its sharp "A" pillar corners and the change in angle where the hood and windshield joined. Ideally the hood and windshield should be integrated into a single curved shape with rounded corners at the "A" pillar locations.

a pillar
 

Thats great always wonder why Saab had the rap-around windshield with the a pillar on the side, good thinking on there part I just wish they got the back right, its like 30 degress

i always thought that the closer to flat the windshield is the less drag it would have! you've seen those solar cars that race across the country there pratically flat!

joesgot4 -

That's what I was thinking. Maybe they are compromising between a teardrop shape and solar panel access?

The Prius hood and windshield are almost a continuous line.

CarloSW2

Hello -

As I was getting popcorn, my wife saw a "wash and wax your car for better MPG" add/trailer in the movie theatre.

I wonder if the local car washes ponied up for the ad?

CarloSW2

wax doesn't help out the cars fuel efficiency nearly as much as clay-barring the car.

Using claybar, smooths out every little groove, removes dirt that can't be seen by the naked eye. It makes the body panels of the car perfectly smooth which increases fuel mileage a bit more than just wax. If you use both, they will definitely increase fuel mileage much more.

The fellow that was in the Hot Rod magazine article that I refered to earlier is the head of the A2 windtunnel A2WT HomePage
He helped design the EV1.
He stated that it didn't matter if your car had the "worst rattle-can paint job". Your .Cd would remain unchanged.

I agree, a dirty car won't use ANY more fuel than a clean one. Hmm, I wonder if taking a ball-peen hammer to a car, to dimple it like a golf ball, would improve it. :D

washing it helps if it's caked in mud like mine was this week. My gas mileage shows this last tank it was down lower then my average