Will a car that is waxed get better MPG than a dirty car due to less friction and smooth air flow? I believe it would and I’ve got dinner at “Denny’s” hanging on your answer.
Only if you can drive at NASCAR speeds on a track. Normal driving it may add 0.00000000015 miles per gallon.
2 Likes
The answer is YES a clean car gets better MPG’s
And Mythbusters proved it
3 Likes
Interesting myth busters info here. I would have thought loosing a few pounds or going to the restroom before driving would be more effective.
1 Like
I don’t think the increase in mileage is noticeable.
That’s just sad. 
2 Likes
I like Denny’s! Wish we had one around here.
I didn’t click the Mythbusters link, but sort of remember the episode. The tests they did were on the extreme cases; you’re talking about waxing.
I have to agree with @VOLVO_V70 that theoretically, yes, it will be better, but not enough that you could measure. Like saving 1 gallon of gas every couple decades.
Don’t know if that’ll get you the dinner. Maybe a desert, though.
About 30-40 years ago I remember an airline repainting their whole fleet with a paint that had a smoother surface resulting in less air friction. I vaguely recall it would save $30K/year per plane.
@Rich28: Given the above, I would say a waxed car does get better mileage. Perhaps viewed best as “in theory”. At car speeds it’s likely infinitesimal and probably only measurable in a very controlled lab environment.
Having actually done a before and after weighing, I would say that’s the mother of all bowel movements or bladder voids.
2 Likes
Yes, those sorts of improvements can pay for themselves in the higher-performance, more extreme situations. It reminds me of all the various extensions I see on truck trailers nowadays. Improvement of 0.1 mpg could save enough fuel to justify the install expense and extra trouble of these extensions.
For most of us driving our personal vehicles the biggest impact on gas mileage is how we drive.
1 Like
If you recall, in the movie Strategic Air Command, the General tells Jimmy Stewart that a scuff from a shoe on the wing of a B47 would reduce speed by 20 MPH!
But a plane at 500 MPH, is lot different than a car at 70 MPH.
1 Like
I take Mythbusters experiment results with a grain-of-salt. Their experiments are not always the best or conclusive. Fun to watch though.
A clean car MAY give you better gas mileage, but I don’t think it’s measurable.
I do know that some fighter jets - just a scuff on the wing will cause a noticeable performance difference.
3 Likes
I doubt that’s true in real life, but I don’t know that. @the_same_mountainbike - does that sound right? You worked on B-52s, right?
That was one great movie. I think I’ve only watched it 50 times over the years.
So, yes, definitely!
Hey, a Moon Over My Hammy is at stake here, we owe it to the guy to get him fed. 
2 Likes
only if you drive downhill and with the wind
Does improved mileage (less gas used), if present, offset the cost in water, detergent, etc to wash and wax the car?
1 Like
Not really, but it will be a “happier car” according to Colonel Hogan in “Hogan’s Heros” as they told Schultz when trying to sabotage Commander Klinck’s car,…
The best way to get better mileage is to inflate the tires more and only carry skinny passengers.
right?? A yes is a yes, folks! minuscule amount or not- yes is the answer!
2 Likes
If Mythbusters proved it I am a believer. I would have guessed “No” because the air flow over a car isn’t that dependent on friction of the surface. Shapes like dimples can change airflow, but the Reynolds number and whether the flow is laminar or not don’t change based on surface friction that much if I remember fluid dynamics. I was just a kid, so I may be wrong.