luggage rack

I've always heard that a luggage rack will cut 1-2 mpg highway miles with the air disturbance it creates.
True, flase, undetermined?
On my 78 Caprice classic the luggage rack also has an airfoil on the rear of it that directs the air down towards the window.
Is this functional in any way or purely cosmetic?
My thoughts with my wagon are mild custom wo/luggage rack.

 

Some cars needed a way to keep the exhaust fumes from coming back in when the rear gate window was open.

Here's a good 2-part tech on airflow:
http://www.autospeed.com.au/cms/A_2455/article.html

http://www.autospeed.com.au/cms/A_2456/article.html

 

Makes sense!
I'll have to dig a bit deeper on that one.
Thanks for the articles. There's always something to learn.

 

Bob, I'm planning on doing some of the ideas in this 3-part article:

http://www.autospeed.com.au/cms/A_2159/article.html

http://www.autospeed.com.au/cms/A_2160/article.html

http://www.autospeed.com.au/cms/A_2162/article.html

Especially the undertray in parts 1-2. Major drag reduction and cheap enough to prove out and/or keep.

 

I like the undertray idea just not sure about road clearance.
Might not be to hard to make one easily removed for highway use only.

 

That's what I'm thinking too. Snow drifting is an issue here, in the city.

 

This one might give you some lift at the nose. I just don't want to change the look at the front, unless I swap to a Mustang or Capri front clip:

http://www.autospeed.com/A_109937/cms/article.html

 

Yea, a lot of the boxy wagons wouldn't quite fit the front spoiler look. As for snow drifts, I have a visual of the movie Christmas Vacation when the family wagon launches into the Christmas tree lot.

 

The last article about the spoiler/splitter has some good height/speed graphs comparing the original height and height changes with the custom unit. At 70 KPH they don't compare, but at 140 KPH, they get a 29 mm lift (1.5"). My issue with it, is that a loaded cargo area would do that and more on mine. I'd need a cushion to see over the nose!, But seriously, other than the added height, I don't think the extra frontal drag would make the car anymore fuel efficient. The undertray definitely, but not the spoiler. The little wheel dams make more sense (from the first 2 articles).

 

Well you could test. Three tanks of gas with it on and figure average mpg and three tanks with it off and average mpg.

I personally doubt that the auto luggage racks could make such a large difference. The airfoil on the back was indeed to keep the exhaust fumes out but the side benefit was that it would also keep the rear window clear of dirt from dirt roads and acted to keep the rain cleared on the highway for good visibility.

 

Especially since we rarely drive at the speeds where the roof rack could have a measurable impact on fuel efficiency. On the Eco-modder website, they are proving that smooth wheel discs are saving a lot of fuel, but they're not really appealing.

http://ecomodder.com/forum/showthread.php/experiment-smooth-wheel-discs-tested-b-4-6-a-4368.html

Good section/forum on aerodynamics too. These guys post MPG results:
http://ecomodder.com/forum/aerodynamics.html

Lots of other fuel-saving trials:
http://ecomodder.com/forum/

 

Mine has the nice wire wheel hubcaps. Not sure yet if the stay or go though.
As far as keepint the rear window clean....well...mine will probably be covered in dog nose prints. I can hardly see out the back of my Vibe on most days.
At least with the big wagon the bulk of the dogs wont totally block my rear view.

 

Teach them to drive. That way you get the larger area to enjoy and they can't reach the windshield!

 

But for opposable thumbs the older GSD could drive. I've put more titles on him then a 3rd world General.
The larger area is great though. I can finally haul a nice piece of veneer ply in the rain instead of hoping for a good day in a borrowed pickup.

 

That's right! You can get a whole sheet inside. Mine's too small. I use my trailer on a sunny day, for veneered panels.

Used to raise hunting dogs, when I was a kid. My dad was passionate about his dogs too. Except for cleaning up. 22 dogs, at one time. I was always is sh!t, at the ripe old age of 10!