How do aero mods increase MPG?

There are aero kits, but don't expect too much. Your Prius already has pretty decent aerodynamics in its factory trim.

Tom

 

Most 'Aero' kits are cosmetic, for show. Those that are functional, are to increase downforce, not reduce Cd. Sorry.

 

Hahaha, the truth is, they don't. In fact I probably get worse mileage. Ever since I lowered my car I've been driving harder, and that's worse for your mpg than not having the aero mod.

I can only imagine what a body kit and new rims would do to my driving behavior.

 

I think some people have done their own, particularly on the underside of the car. I would think the front grill, lower air dam could be improved, but it would be hard to get a professional appearance there.

 

mods try to/claim to accomplish one or more of the following:


-weight reduction
-rolling resistance reduction
-increased aerodynamics
-increased electric range
-increased engine/fuel performance

 

The hard truth is; it is difficult to significantly improve the Prius'
aerodynamics. As it comes from the factory, it has either the best or
second best mass production car aerodynamics.

That said, you can achieve minor improvements with things like disc
wheel covers, wiper and mirror deletes, door handle shaving, lowering
and rear wheel skirts. Perhaps as much/little? as 1% each, about .5
MPG each.

The Bonneville speed record holding Prius looks pretty tame:


Although you can find a few "aero kits' that would seem to be very
aero, their best ad copy says the add-ons wont hurt the OEM aero.
(But they will do some serious damage to your wallet.)



There is strong evidence to suggest that if you threw caution and
buckets of cash to the wind, you could seriously improve the Prius
aero. It would look something like this PhotoShopped image:



Automobile aerodynamics is a very complicated art/science.
There is an awful lot on 200 MPH race car aero on the 'Net.
But that is very specialized stuff, hardly applicable to passenger cars
at legal highway speeds. Here are some places to start that do apply:
[ame=http://en.wikipedia.org/wiki/Automotive_aerodynamics]Automotive aerodynamics - Wikipedia, the free encyclopedia[/ame]

Car Aerodynamics 101
Improving Aerodynamics to Boost Fuel Economy; Edmunds.com

Lastly, at Fuel Economy, Hypermiling - EcoModder.com you can read
what folks are doing out on the street to improve the aero and MPGs on
many types of vehicles, including Prii.

Hope this helps.

 

2nd best production aerodynamics last I heard. I agree on what you said about it being hard to improve, but one reason the Bonneville run Prius looks close to stock is that they were trying to get a Production class set up for hybrids and Production classes at Bonneville are limited in what aero modding you can do.

Got Hybrid? - Sport - Auto Reviews - Car and Driver

I would like to also see some Prii running in some of the more radical classes where aero mods aren't so limited.

 

Really? Some of their mods seem quite illegal.

 

It's been a long time since I have been to B'ville.

Which mods and which SCTA rules?

 

i think the one where they block the grill? I dont remember. Basically it makes the car go much faster.

 

It went 130.8 in class and 3.5 mph faster after they blocked part of the grill and taped seams. AFAIK, it was legal for the official runs.

 

Nah nah I'm talking about it being illegal for STREET use.

 

Hi KS,

Check out Ecomodder.com aerodynamics forum.

They have tested flush hub caps, which are easy to do on the 2nd Gen Prius, as I did - wrapping the trim rings with .010" thick aluminum sheet. Ecomodder tests indicated 2 to 4 % improvement in highway mileage (60 mph?) on traditional cars. On a car where the engine can decelerate to get an optimum ratio, it should be a little better than that.

I relocated my license plate over the grill. This helps block air flow into the engine compartment, and thus friction drag. Its Ok around here to do this, as we are not climbing desert mountains. More like coasting between stop lights. And since the engine shuts off at those lights, the extra cooling is just not needed.

Other grill blocking was applied in cold temperatures. An automatic, variable, reliable grill block is a bit of goal for lots of Prius drivers. Not as needed on the Gen 3, with its exhaust heat recovery system. But a very good thing of the Gen 2 especially below 20 F.

I also added turbulators to the upper third of the A-pillar. Tuft testings showed these helped a little on the 2nd Gen, I have not repeated the experiment on the 3rd Gen. The 3rd Gen is different in this area (lower slope, deeper insets), and may not need the turbulators.

On my Gen 3, I have added grill dams, to prevent air hitting the blocked portion of the grill from spilling into open slots in the grill. The air should just spill outboard from being trapped in pockets formed by the bumper fascia, grill dam, and filled in grillwork.