Can Slippery Wax Improve Gas Mileage?

No, not really. You have to maintain a laminar flow for that to make any difference. The normal surface on the Prius is smooth enough for the flow.

Tom

 

so you would have to cover the car with a rolling surface.. like huge delivery belts (but flush).. or some magical moving liquid that moves with the wind?

that would be cool...

An outer shell that actually moves or propels would be pretty awesome

 

Have a look at this interesting site on car aerodynamics...
Car Aerodynamics 101

 

when i google for 3m perfect fit, all i get are pages for the rubbing compound, and that is something you want to use very sparingly..

 

They might not get better gas mileage, but I am sure cars run better when they are clean

Mike

 

I think you hit on a million dollar idea - you start selling the wax and claim it will give you better MPG. You might try selling it as a supplement like those "products" that claim to lengthen the size of a man's you-know-what to avoid jail time...

 

I read a study a long time ago that reported a clean, waxed car does improve gas mileage, but only minimally - such as 1 - 2 mpg, as does rolling up the windows. Laminar flow is best but difficult to achieve due to all the components that add parasitic drag such as the door handles, bumpers, radio antenna, muffler, etc.

The obvious largest factor that affects gas mileage is your tire pressure. Under-inflated tires will rob your performance by as much as 5-10mpg! And there are other disadvanteges such as radically increased wear and danger to premature failure due to the excessive amount of heat generated.

 

Odd that they didn't include the most aerodynamic production vehicle ever - the EV1.

Well, yes, actually. As long as you aren't looking for what I'd call *significant* savings. But I'll tell you what - the EV1 paint was specifically manufactured and applied to be as smooth as possible purely for aerodynamic advantage. I believe the car had six fine coats of paint. Honestly, you've never seen a better production paint job than what the EV1's came with. Smoothest and most durable paint I've ever experienced.

 

By significant I mean measurable. The boundary layer flow on any production car will be the same with the smooth factory paint job or with some slippery coating. The shape of automobiles is just not aerodynamic enough for a coating to make any measurable difference. Even cars with good aerodynamics have a big layer of detached air at the boundary.

You could possibly make a measurable difference with active boundary layer control, where thousands of tiny holes are used to suck away the turbulent boundary layer. It works on jet aircraft, but I imagine the power to do it would overshadow any gain on an automobile.

Tom