Pizza Sign Placement
 

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.

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. :confused:

Put a plexi boat tail on it.

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

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.

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.

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.

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.

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

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

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.

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.

There you go. Or if you have a sunroof, stick it just behind the sunroof opening. When out of range of the boss, open sunroof, reach up and remove sign, then close the sunroof. Voila!

Could do like I did when the owners of the pizza shop I deliver for tried to make us put signs on our cars. I looked them right in the eye and said that's not going to happen because I don't like the idea of making it any more obvious that I could possibly be carrying a decent amount of cash to be robbed for. Never did put the sign on my car once.

an aero friendly alternative would be window stickers or magnetic signs. the first would be cheap, but not possible to remove when not needed the later perhaps a little more expensive but easy removed

both would be aero neutral and maybe even more noticable than the roof mounted sign.

airfoil sign
 

Locally,Papa John's Pizza has a low drag,symmetrical airfoil shaped illuminated sign that their delivery drivers suction cup to their car's roof.
You might light a fire under your boss and see if they'll ditch the parachutes your now using and come into the 21st Century with the better advertising.
Looks like they would soon pay for themselves at the rate your losing.

I respectfully disagree. Everything that I've read (which has been a lot) has provided that speeds as low as 25 mph can effect efficiency.

You're right in thinking that 35-40 mph makes more of a difference than 25 mph, of course. However, it is at this lower speed that we begin to see aerodynamics at play.

HAHAHAHAHAHAHAHA...awesome.

I also doubt you've lost 6 MPG from a small sign.

That being said, I've actually noticed some of the signs for cars seem to have been built with aerodynamics in mind! They have a teardrop shape with boat tail when viewed from above/below. I can't seem to find a picture of one, however.

Verdann -

Ask if you can have two and figure out how to mount them in the rear window on each side. You might suffer from interior glare, though, so you'd need a black cover so that only the window-side is glowing.

CarloSW2

If you know where your flow separates, put the sign about 0.5m upstream. It's larger than optimal, but it might still do some good. I'm going to have to wait 'til I get home from work to reference the paper that recommendation is based on.

I' m glad Dr. Frank is not going to cut on my car (lol)

If you have some access to clear plastic. you could basically build front and rear ramp slopes to smooth it all out.

I agree that the nose to tail would be cleaner.

Now for strictly a purist aero talk, I'm picturing a typical '92-94 Metro here??

Not regarding police laws, I'm thinking the cleanest possible air position would have the sign nose to tail in the middle of the hood like a monster hoodscoop.

The IRS allows you to deduct whatever amount per business related mile. If your company requires you to carry their advertisement in a way that makes your vehicle less efficient and they do not reimburse you for that then the requirement is above and beyond the IRS' deduction: it is a penalty for being a XXXX Pizza employee. Either lose it in a ditch every time you hit a speed bump or find some shyster who can spell "class action."

What company? Domino's has a tear-drop shaped one that mounts to the window. Papa's, Domino's, and Gatti's (local) all have arrow shaped ones that mount to the roof.

I worked at Domino's for 2 years, we'd screw around with each other's car. Very lax rules about toppers, but a few times we'd use them to get good parking at businesses. Sticking them on the tailgates of coworkers' trucks and SUVs was always a fun way to screw with each other, since it was out of sight. The magnets were so strong, they never fell.

Having a class action law suit over a pizza sign? Get over it...

Quite the necromancy job on a year old thread. I ended up finding the perfect solution to the placement of the sign.... On the storage rack in the store. I just stopped using it.

on the storage rack
 

That's the most elegant solution.Hope management is okay with that.:thumbup:

Depending on your area do you really get up to the speed in which it will hurt your fuel economy ? The stop and go (I'm self employed and mobile) slams my fuel economy. Yes, I know some delivery drivers go like Mario Andretti, but............while you're at it I'd like a thin crust pepperoni...fat boys like to eat :D