I notice when I drag the back of my hand across the nice clean clear coat, there is a certain amount of grab. Anyone know how much high speed drag is affected by a good super slick top coat? Must come into play when you are traveling at higher speeds. I find about 58mph is the most efficient for my FFH. I'm thinking of putting a wax coat of something that will make it as slick as possible. Any ideas on that one? Noel

Well you might be on to something. A slick boat definitely glides better in water than one all covered in algae and barnacles.

That said there is a reason they put dimples on golf ***** so air might be different than water?

I've not noticed a difference between clean or dirty with my hybrid but I rarely drive over 45 mph so my car is not a good example.

Most likely because the difference at 'reasonable' speed is too small to measure.

Now, if you're going 300+ MPH, maybe having a waxy would be measurable. But at <70, the other sources like tire drag, overall car shape, under-body roughness, and even road surface roughness would be higher by several orders of magnitude.

Another weird thing about air movement - it's not always an intuitive relationship. Witness the dimpled golf ball - some surface roughness actually improves aero performance by introducing 'good' turbulence. So, a super-slick surface may not improve things, and may even make things worse.

So when are we all going to dimple our rides!?

http://www.autoblog.com/2009/10/22/m...-dimpling-mpg/

Mythbusters did it, got 11% improvment!

2008 Escape Hybrid FWD
Ice Blue w/Chrome Pkg
Moonroof - Leather Premiem pkg
http://hybrid08ok.x10hosting.com/index.htm
Mods: Tint front to match, Cargo Cover, Keyless Pad, Flaps, Side Moldings.


2000 Expedition Eddie Bauer
1965 Falcon Futura 4 Door I6

Mythbuster solve this question quite well the other day.

I'm not one that keeps a car washed and waxed all the time and I somehow knew washing and waxing never improved my mileage. I wasn't aware that a dirty car improved mileage until I saw mythbusters the other night. I've been putting off washing my '09 FEH because a month or so ago I was ask to be in a documentary on Hypermiling the BMW X6 ActiveHybrid. They said they wanted to include footage of me and my '09 FEH so I put off washing it till I had to drive to Miami for the shooting on 11/6/09. The FEH got real dirty during this time but my mileage was increasing. About 3pm on 11/5/09 I took the FEH to the car wash and had it detailed and hand waxed. Since that time I noticed a decrease in MPG of about 10%. I've never noticed that big of a drop in just washing the FEH but waxing it really made a difference for the worst. No question in my mind that a dirty FEH gets better mileage than a waxed FEH.

The '09 FEH is slowly getting back to normal now that a layer of road dirt and dust is starting to coat the wax.

GaryG

I like this answer: "Not really. You're not going to go fast enough for it to make a significant difference. If it mattered, you would see the airlines waxing their jets...they don't. It will make your car look cool though."

Red