Rear spoiler and MPG question?

[markuszoom5]

I have a 2010 Mazda 5 Sport automatic with side sills and rear spoiler (all factory) attached by dealer. Do you guys think that the rear spoiler and the side sills improve or worsen gas mileage? What does everybody think?

 

[VenomDesign]

I think it is the most funny question i've seen on this forum. lol

 

[markuszoom5]

Why?

Why is it funny?

 

[IPitboy777]

Why is it funny?

deff makes it worse on the gas mileage but its maybe like 5cents per tank lol, but it does increases the amount of drag, but come on are you serious now? get a honda hybrid!

 

[was98strat]

It's a bit irrelevant, the rear spoiler is part of the hatch and not removable!!! The spoiler is a factory option, the dealer cannot add it on. Side sills are also factory, never seen a Mazda 5 without them. Both GS and GT trim levels some with them standard. Doubt the sills have any impact on mileage other than to make the car look substantially better with them on. I'd think the car would look strange without them. G

 

[markuszoom5]

now wait a minute

It's a bit irrelevant, the rear spoiler is part of the hatch and not removable!!! The spoiler is a factory option, the dealer cannot add it on. Side sills are also factory, never seen a Mazda 5 without them. Both GS and GT trim levels some with them standard. Doubt the sills have any impact on mileage other than to make the car look substantially better with them on. I'd think the car would look strange without them. G

Look, not to be rude. I have seen several 2008-2010 mazda 5's here where i live, and some of them have no side sills or rear spoiler. The washer nozzle is then sitting on the trunk lid and does not come out of the spoiler like mine. I have also seen 5's without side sills, and you can see all the rust and dirt on the edging of the frame.
Also, my 2010 mazda 5 was a brand-new leftover, it sat @ the dealer because the couple before me ordered the car. They wanted 6disc-chgr, side sills, and rear spoiler as part of the popular equipment package @ that time. If you don't belive me:

CHECK OUT MY WINDOW STICKER THAT I POSTED ON THIS FORUM.

 

[Orangutan]

It's a bit irrelevant, the rear spoiler is part of the hatch and not removable!!! The spoiler is a factory option, the dealer cannot add it on. Side sills are also factory, never seen a Mazda 5 without them. Both GS and GT trim levels some with them standard. Doubt the sills have any impact on mileage other than to make the car look substantially better with them on. I'd think the car would look strange without them. G

Uh, what? Side sills and spoilers are both optional equipment that are not on the Sport trim but are on the Touring and Grand Touring trims here in the U.S. Why would you not be able to add an optional body element? That doesn't make any sense.

 

[Orangutan]

deff makes it worse on the gas mileage but its maybe like 5cents per tank lol, but it does increases the amount of drag, but come on are you serious now? get a honda hybrid!

Are you sure it increases the drag? On my Altima the spoiler decreased the drag. It all depends on the shape and placement of the spoiler.

 

[was98strat]

Uh, what? Side sills and spoilers are both optional equipment that are not on the Sport trim but are on the Touring and Grand Touring trims here in the U.S. Why would you not be able to add an optional body element? That doesn't make any sense.

the rear spoiler you are talking about is integrated into the rear hatch. if you want to add the factory spoiler to the rear hatch, you have to change out the whole rear hatch. it's not a dealer option.

having said that . the side sills are standard equipment on both GS and GT level trims. the only "add on spoiler" that is available looks completely like an addon and is VERY different than the GT spoiler that is integrated into the rear hatch.

 

[flcruising]

was98strat is correct about the rear hatch. Integrated.

The side sills are not aftermarket as there are holes down the side of the body sheet metal that the sills clip into. IOW, this isn't a dealer installable option either.


Sorry, forgot to post about your question. Unless these guys have done some testing or seen the data, they have no idea how these body parts affect the drag coefficient. That being said, I wish there were a way of diverting the airflow down the back of the vehicle as a kind of air wash because the rear end is always the dirtiest. Like what some older SUVs had. I've even contemplated cutting holes in the spoiler but quickly decided against it.

 

[Rockin03mp5]

guys remember, canada is different.

the canadian models differ from the us.

the base sport in the us did not have a rear spoiler or side skirts. it could be added with the "popular package". all of the history on here shows the spoiler is integrated with the hatch, so it cannot just be removed.

i think flcruising said it best. there is no evidence that it would help or hurt mpg.

the only effect i can see would be the loss of weight, but again, that would be minimal. might as well take out the spare tire and seats as well.

 

[chitownpete]

I think thats a good question, nothing funny about it. Unfortunately it's too close to call without extensive and expensive testing. I remember a Mustang test where they picked up 3 mph top speed by removing the rear spoiler.

 

[DKaz]

Are you sure it increases the drag? On my Altima the spoiler decreased the drag. It all depends on the shape and placement of the spoiler.

Did you just say that with a straight face?

It's a bit irrelevant, the rear spoiler is part of the hatch and not removable!!! The spoiler is a factory option, the dealer cannot add it on. Side sills are also factory, never seen a Mazda 5 without them. Both GS and GT trim levels some with them standard. Doubt the sills have any impact on mileage other than to make the car look substantially better with them on. I'd think the car would look strange without them. G

None of the Canadian GS's have rear spoiler, GT only. The 06-07 GS had side sills though.

06-07:

08-10:

12+:

 

[was98strat]

hmmm, the car really needs the side sills, if it's not standard on the later model years up here in Canada, most people must be ordering them with the sills anyway.

 

[Orangutan]

Did you just say that with a straight face?

What?

 

[DKaz]

hmmm, the car really needs the side sills, if it's not standard on the later model years up here in Canada, most people must be ordering them with the sills anyway.

Looks ok either way. I happen to want a GT so it just happens to come with it.

What?

Spoilers do NOT increase aerodynamics!

 

[Orangutan]

Spoilers do NOT increase aerodynamics!

Spoilers can decrease the drag on a vehicle, but they can also increase it. Like I said earlier, it depends on the vehicle and the spoiler.

 

[thaxman]

Wow, this is becoming a catfight.

Obviously, side sills have some weight to them, which would mean a net DECREASE in mpgs, but, because they restrict some of the air that can flow under the body along the wheelbase, it may be possible they INCREASE mpgs as well. My vote: no noticable difference.

As for the spoiler, they are either aesthetic or functional. Most functional ones are either wings (think Lamborghini) or scoop (think '74 Camaro). These decrease drag as they can significantly alter airflow. I read that Road & Track (I think) tested several 200+ mph cars and found that while the Lambo's wing kept it steady at high speed, they couldn't get past abt 180 w/it on the car. Without it, the car was squirrely at speed, but they could get it almost to 200. The scoop style spoiler pushes the body downward, loading the drive wheels on RWD cars for traction, but they are probably a disaster in the mileage dept. Our spoiler does neither. I doubt it has much effect on mpgs, other than creating a sharp edge at the trailing edge that may enhance wake turbulence. Again, it is probably minimal.

Lowering ride height will probably increase mpgs more than either of these, while adding larger wheels and wider tires will probably decrease mpgs more than either of these.