Pizza Sign Placement

[Verdann]

So I work for a pizza place that makes us put these toppers on our cars. In doing so I have lost 6mpg. I was wondering if anyone out there had any experience with where to put it on the roof of my car to minimize the effects of the topper. We have to have it run across the width of the car (Door to Door) The length and Height dimensions are 16.5" W x 6.38" H. For a picture I found the supplier companies website Mini Quad Car Top Signs. I drive a 1994 Geo Metro 3 cyl 5 speed 2dr hatchback. I am already doing what I can driving wise.

[Frank Lee]

I'm told increasing the wake behind a vehicle reduces drag so it should be all good. Or at a spoiler to it.

I jest!

My WAG is it doesn't really matter; positioned forward and there is likely a turbulent wake all the way back; positioned rearward and... there is still a turbulent wake all the way back.

Put a plexi boat tail on it.

[lunarhighway]

i saw a piucture a while ago of a police minivan, that had a "spoiler" at the upper edge of the windshield, it basically continued the angle of the windshield a bit beyond the roof. my guess is it was put there to guide the air over the police lights wich where somewhere at the b pillar on the roof.

perhaps you can it so that along with the windshield the pressure bubble in front of the sign would make a smooth virtual path for the air to follow? just guessing

[RobertSmalls]

At the same time as you installed the sign, you also changed the routes you drive on. I'm guessing the many short trips, unfamiliar routes, and traffic, cost you much more than the <1ft² sign.

[comptiger5000]

How fast are you typically driving when you have the sign up there? If it's not over 35-40mph, the sign itself will make very little difference.

[DonR]

Would mounting the sign up off the roof several inches help? It would allow some air flow to travel under the sign & have a chance at staying attached?

Could a piece of clear plastic shaped like the top half of an airfoil mounted a few inches away from the top & sides of the sign deflect air downward to reduce drag.

Drill holes in the white parts of the sign.

[Verdann]

Going to and from the neighborhoods travel speed is between 35 and 45 mph. Altering the sign is not possible (owned by the company). Thanks for all the input. I think I'll play around with the placement to see if it makes a difference. was just curious if anyone already had. I'll try to remember to track my results and post them as I get them.

[BamZipPow]

Are you allowed to put it on the trunk deck/lid?

How about rotating it 90° and have it point from nose to tail?

[Patrick]

Pick up the pizzas and drive a block away. Take the sign off and throw it in the trunk. Deliver the pizzas. When you get a block away from the pizza business, put the sign back on the roof. Repeat.

[Frank Lee]

Too much stopping. Mount it to roof, cut hole in roof around the perimeter of the sign base, attach raise/lower mechanism and also self-actuated sliding cover for the hole.