Fuel Economy Tip - Wash and Wax?

mimo2005 · 08-25-2006, 12:48 PM

Apparently, washing and waxing your car will help you get seven-percent better gas mileage.

http://www.dailyfueleconomytip.com/?p=62

For some reason, I find that hard to believe

**Fox** · 08-25-2006, 12:57 PM

I don't think that's true. I've heard that it'll increase by about 2%, and that surely won't offset the cost of the washing materials.

Switching to biodiesel (or even regular diesel at this point in time) will save you far more in fuel and maintenance. Plus, if you plan on keeping your vehicle for a long time, diesel engines last well past 300,000 miles when cared for.

ebackhus · 08-25-2006, 02:38 PM

I really doubt that the tiny specks of dust and grime that mar my car's finish will equate to nearly 7% savings on fuel when removed. Maybe if they were teh HUEG and stuff then I'd believe it.

**Midnight Tech** · 08-25-2006, 06:22 PM

You ain't seen my truck....it's faded so much on top....it looks like it's painted flat blue...a little wax may just help my fuel economy.

daamon_vexion · 08-26-2006, 12:46 PM

ya, 7% seems a bit high... 3% mebbe, but the cost of washing a car? you insane a little dish soap, a 5dollar tub of Turtle Wax, and water... i think that it will offset a little bit...

Zazula · 08-27-2006, 02:47 PM

The resulting fuel economy is mainly a function of the speeds maintained vs repsective times. You cannot use a car for five-mile drives inside the city and expect it to burn less fuel because you've waxed it... Keeping a car clean and waxed will mostly assure ladies will deign coming in without frowning (which is a benefit in its own good). Of course, GI Janes will highly value an irrevocably mudded jeep, so act accordingly.

Now, for all of you who adore diving into simple calculations in three-dimensional compressible fluid flow equations (my favorite pastime), here is an Index to Coefficient of Drag for Many Vehicles Plus Index to Horsepower vs Speed Curves. Use coefficient variations depending on how clean your car's surface is and enjoy! (Funny note: Hummer H2 has 4.5 times the aerodynamic drag of Toyota 2000GT.)

And now for the most interesting part: Who said that a laminar flow is always the most desirable? Have you ever noticed those bulgy spherical parts in the front of big ships? Haven't you ever wondered why are they there? Shouldn't they spoil the flow?

Well, that's exactly the point: to spoil the flow! Having a laminar flow is great, however the boundary layer inevitably thickens and becomes less stable as the flow develops along the body, and eventually becomes turbulent, the process known as boundary layer transition. So, a laminar boundary layer tends to separate from the surface. Such separation causes a large increase in the pressure drag. In these cases, it can be advantageous to deliberately trip the boundary layer into turbulence at a point prior to the location of laminar separation, using a turbulator. The fuller velocity profile of the turbulent boundary layer allows it to sustain the adverse pressure gradient without separating. Thus, although the skin friction is increased, overall the drag is decreased.

Suggested reading - one of my most beloved books: Boundary-Layer Theory (by Herrmann Schlichting, Klaus Gersten, E. Krause, H. Jr. Oertel, C. Mayes)

mimo2005 · 08-27-2006, 04:44 PM

that's interesting zazula .

08-25-2006, 12:48 PM	#1 (permalink)
mimo2005 Manager, The Relaxation Room/Analyst, Security Team Join Date: Oct 2004 Posts: 11,131 OS: xp	Fuel Economy Tip - Wash and Wax? Apparently, washing and waxing your car will help you get seven-percent better gas mileage. http://www.dailyfueleconomytip.com/?p=62 For some reason, I find that hard to believe __________________ TSF has outgrown its server, again. Please help "Gutta cavat lapidem, non vi sed saepe cadendo"

08-25-2006, 12:57 PM	#2 (permalink)
Fox TSF Enthusiast Join Date: Sep 2002 Location: NJ Posts: 7,752 OS: XP Pro, CentOS My System	I don't think that's true. I've heard that it'll increase by about 2%, and that surely won't offset the cost of the washing materials. Switching to biodiesel (or even regular diesel at this point in time) will save you far more in fuel and maintenance. Plus, if you plan on keeping your vehicle for a long time, diesel engines last well past 300,000 miles when cared for. __________________ Antec Neo Power 500W, ABIT IP35-E, Intel E2180@2.66Ghz, Corsair XMS2 2x1GB DDR2-800, PNY 8800GT, 320GB Seagate * lazy college student alert *- If I've inadvertently ignored a thread, please Let me know about it Have I helped you solve your problem? Donate to Techsupportforums Klart Skepp!

08-25-2006, 02:38 PM	#3 (permalink)
ebackhus Manager, Design Join Date: Apr 2005 Location: SATX Posts: 12,767 OS: WinXP Pro SP3 My System Blog Entries: 25	I really doubt that the tiny specks of dust and grime that mar my car's finish will equate to nearly 7% savings on fuel when removed. Maybe if they were teh HUEG and stuff then I'd believe it. __________________ ----------------------------- There are no dumb questions, unless a customer is asking them. Help in the fight against cancer and other serious illnesses.

08-25-2006, 06:22 PM	#4 (permalink)
Midnight Tech Admin/Head GreaseMonkey/Igor's alter ego/Grand Exalted PoohBah Join Date: Dec 2001 Location: SC Posts: 2,638 OS: Windows XP SP2/Windows 98SE/Fedora Core 6/RH 7.2 with Autopoint	You ain't seen my truck....it's faded so much on top....it looks like it's painted flat blue...a little wax may just help my fuel economy. __________________ Please post all questions in the appropriate forum. Questions sent by email or PM will not be answered. Sharing my life...with my Imzadi! Interested in Trek gaming? Check out the Dynaverse! Proud supporter of the Carolinas Aviation Museum. If we have helped you in any way, please donate to keep TSF up and running!

08-26-2006, 12:46 PM	#5 (permalink)
daamon_vexion Resident Soldier Join Date: Aug 2006 Location: Iraq (temp) Wyoming Posts: 560 OS: Windows XP Media Center My System	ya, 7% seems a bit high... 3% mebbe, but the cost of washing a car? you insane a little dish soap, a 5dollar tub of Turtle Wax, and water... i think that it will offset a little bit... __________________ *And the Infantry Sayeth unto the Lord "Thou hast made us the Queen of battle, and Artillery the King, surely thou knowest what the King does to his Queen?" And the Lord replyeth, "Right On!"*

08-27-2006, 02:47 PM	#6 (permalink)
Zazula Manager Emeritus, I'm blond, James Blond Join Date: Apr 2006 Location: Athens, Greece Posts: 7,643 OS: Win XP Pro SP2	The resulting fuel economy is mainly a function of the speeds maintained vs repsective times. You cannot use a car for five-mile drives inside the city and expect it to burn less fuel because you've waxed it... Keeping a car clean and waxed will mostly assure ladies will deign coming in without frowning (which is a benefit in its own good). Of course, GI Janes will highly value an irrevocably mudded jeep, so act accordingly. Now, for all of you who adore diving into simple calculations in three-dimensional compressible fluid flow equations (my favorite pastime), here is an Index to Coefficient of Drag for Many Vehicles Plus Index to Horsepower vs Speed Curves. Use coefficient variations depending on how clean your car's surface is and enjoy! (Funny note: Hummer H2 has 4.5 times the aerodynamic drag of Toyota 2000GT.) And now for the most interesting part: Who said that a laminar flow is always the most desirable? Have you ever noticed those bulgy spherical parts in the front of big ships? Haven't you ever wondered why are they there? Shouldn't they spoil the flow? Well, that's exactly the point: to spoil the flow! Having a laminar flow is great, however the boundary layer inevitably thickens and becomes less stable as the flow develops along the body, and eventually becomes turbulent, the process known as boundary layer transition. So, a laminar boundary layer tends to separate from the surface. Such separation causes a large increase in the pressure drag. In these cases, it can be advantageous to deliberately trip the boundary layer into turbulence at a point prior to the location of laminar separation, using a turbulator. The fuller velocity profile of the turbulent boundary layer allows it to sustain the adverse pressure gradient without separating. Thus, although the skin friction is increased, overall the drag is decreased. Suggested reading - one of my most beloved books: Boundary-Layer Theory (by Herrmann Schlichting, Klaus Gersten, E. Krause, H. Jr. Oertel, C. Mayes) __________________ "Time is the wisest because it discovers everything" Thales of Miletus (ca.624BC-ca.546BC) "Everything flows, nothing stands still." Heraclitus of Ephesus (ca.535BC-475BC) "One thing I know, that I know nothing" Socrates of Athens (ca.470BC–399BC)

08-27-2006, 04:44 PM	#7 (permalink)
mimo2005 Manager, The Relaxation Room/Analyst, Security Team Join Date: Oct 2004 Posts: 11,131 OS: xp	that's interesting zazula . __________________ TSF has outgrown its server, again. Please help "Gutta cavat lapidem, non vi sed saepe cadendo"