Dirty vs Washed Car / Any MPG significance?

[ChewChewTrain]

Might anyone know the MPG difference between a dirty car versus clean car?

Thanks,
Doug
Oakland, CA

[Draigflag]

You're going to be splitting hairs, microfractions. Whatever the difference (if there is One) the time, effort and expense of washing a car isn't going to make any kind of financial sense.

[rfruth]

No noticeable difference here

[rboy159]

A dirty car will have more drag, however, not noticeable in your MPG. As a rule, every 1000 miles I drive, I wash my car or get it washed. Don't want those bug stains to damage the paint.

[spartybrutus]

You will probably drive your clean car more gently...

[campisi]

From what little I remember of boundary layer thermodynamics boundary dictates that, very close to the surface in question, the velocity of fluid flow (in this case air) is effectively zero. Therefore no effect on MPG?

[Jay2TheRescue]

In reality, clean vs dirty is an insignificant difference, unless your vehicle is this dirty...

[trollbait]

Then it might be weight.

[Jay2TheRescue]

That was exactly my thought...