What effect is the spoiler having on MPG?

http://priuschat.com/spoiler-mileage-test-t11877.html

 

I think Brian has some of the '04 & '05 colors but I just used a black one. (my car is driftwood pearl) All around the hatchback window is black so a black spoiler looks great. When I pointed it out to my friend he said "oh, I thought that was something the factory put on".

As you can see from my test the mileage was unaffected. My car has never had the handling and tracking problems some have reported. But I think all Prii get blown around some in the wind and it has helped with that quite a bit. I don't think this susceptibility to wind is a problem unique to the Prius, I think it affects all cars with similar aerodynamics. I can definately see an improvement driving down the gorge on I 84 on a windy day.

 

I think the only two colors that would work for you are black or the same color red as your car.

It is easy to install and comes with directions and a little bottle of alcohol to clean the glass. You just pull the tape off the bottom which exposes the adhesive and press it on. Of course you have to get it in the right place first try.

I did have one small problem, a couple of days after I had put it on we had some cooler weather and both ends popped up, the center stayed stuck down. I pressed the ends down again but they wouldn't stay. I bough a tube of Loctite "stick'n Seal" and after I cleaned under the ends again I cemented them down with the Loctite. It's designed to stick to glass and most everything else. I held the ends down with a couple of little "C" clamps for 10 or 12 hours and everything has been OK since through all sorts of weather. Now as far as I know I'm the only one who has had that problem so maybe I just got one with defective adhesive on it. But like I said it was no real problem and it's good now. You can get the Loctitte "Stick'n Seal" at Wal Mart or an auto parts store for 3 or 4 bucks a tube if you need it but I bet you won't have the problem.

 

How about lowering the rear seats and adding 40 pounds in the back. That should lower the center of gravity and could give a flatter ride.

 

Toyota, or any other car manufacturer, doesn't care about perfection. They care about what will sell. They will ignore any flaw or poor design unless they think it will cost them money, either through lost sales or law suits because it's a safety issue.

 

I think the spoiler on the Prius is not there for downward force. I think it's there for three reasons: 1) to deflect some air across the smaller window on the hatch so it doesn't get dirty as quickly; 2) to fill some air into the "hole" behind the car and thus reduce turbulence, though the tests done by tumbleweed indicate that this doesn't do much; 3) styling.

Besides, I think spoilers don't do much on most cars except add drag. Sometimes you'll see rice rockets with huge ones bolted onto their trunk. The trunk lid can't support more than 300-400 pounds without buckling, so they've got to be contributing less than this or less than about 15% of the weight of the car. Plus, you need the extra force mostly when you corner, but you're usually not going 100 mph when you corner unless you are driving a F1 car on a race track.

 

While that would be very cool, and fit the high tech apect of hte car, you can only get so much at (at most) $30k. If you want all that computer controlled spoiler stuff, buy a $1.2 Bugatti Veyron. It has computer controlled flaps and spoilers and suspension. Of course it also goes over 250 mph, but that's adiffernt matter...

 

Let's keep in mind the distinction between the add-on spoiler that
the referenced thread was talking about, and the STOCK one that
comes with the Prius. Someone needs to do the experiment by
*removing* the stock one and doing test runs, not worrying about
the ineffectual aftermarket glue-on thing. Hmm, I might try this
next spring...
.
I read somewhere, and there's NFW I can dig it up at this point, that
the Prius shape [and quite a few other cars] follows a design that
somehow captures a particularly-shaped pocket of air behind it and
allows the *rest* of the air to flow around that better. In other
words, somehow the design of the spoiler and the air-dam underneath
the trunk, despite looking like the opposite of a tapered airfoil,
are said to have better aerodynamics than simply ending the body
at a corner. I can't substantiate this but maybe some of the stuff
kicking around over at Toyota might mention it...
.
_H*