Ground Effects + Springs = better MPG?

17in wheels with wider tires will give you a decrease in MPG. Also 17in LRR tires are hard to find so you get a double wammy. Expect 5 to 8 MPG decrease when you make the change.

 

You'll never recover from the loss associated with 17s. The effect of springs is negligible and the effect from ground effects can be positive or negative. Without wind tunnel testing you'll never know.

If you don't drive many miles each year then suck it up and put 17s on it. If, like me, you drive 25k or more then the decision is not so easy.

 

I could not see any measureable difference when I added the springs, but I only went down one inch.

 

I spent all day in the sun building an irrigation for a restoration project. I had to get it done before the boy scouts come out to tomorrow morning. In other words, I'm exhausted. lol

 

You would need a wind tunnel with a BIG treadmill so you can measure the REAL effect. The effect of moving air is not the same as a moving CAR.

 

What is the verdic here? I would like just a simple kit, like the Axis 5 but I can not really find it anywhere.

The wheels you knew were going to kill the convo... understandably. I am still doing searches trying to find different OEM wheels. I am still wondering if the CT200 has any 16's available that are thin enough for me to justify.

 

Wouldn't getting a wheel tire combo of the same weight and similar low resistance tires at the same 215 width result in similar numbers with the stability benefits of less rubber on the sidewalls at 16 17 or even 18? Anyone know the weight of the stockers (15 and prius v 17s)? I would baseline from there and aim for same or lighter wheels and tire combo. Tire rack I know provide weights of their wheels and tires.

SPH-D700 ?

 

I'mnot sure what you are asking here. When you upsize wheels you are also making the tread width wider. The Prius comes with very narrow 15" wheels so it is difficult to try and find a 17x6"wheel and a tire to fit it AND be LRR rated. So in practical terms you cannot upsize and maintain OEM 15" weight and maintain tread width and keep rolling resistance the same. 16" and 17" tires simply weight more and will be wider so as a result mpg goes down.

I have a sector very lightweight 17s but the tires weight more than the average 15" tire so despite the total weight increase of only 6-7lbs per wheel, my mpg drops by at least 6mpg due to increased rolling resistance and possibly coefficient drag. It sucks but I have not been able to find a way around this issue.

 

I'd got 2 mpg higher on highway when i lowered my car. It drives way better handling, responsive on highway...:rockon:

 

I'd be curious to review your testing procedures so that we can quantify your results as more than just casual observations and rule out other contributing factors.

In theory lowering the car should help but there is scant evidence to support the theory when applied to the Prius. There are so many other positive effects associated with lowering the car that I support the idea regardless of any mpg changes. I am just careful about attributing mpg changes all willy nilly.

 

OMG stock wheel is only 6 inches wide! Nevermind lol =)

I guess it's not even really the weight more the rolling resistance of the actual tire. Makes more sense to me now thank you. Any of you guys find it scary to have such thin tires for a car over 3000lbs? I suppose the skidpad and 60-0 numbers speak for themselves. Yep, not going to keep that stock =).

 

Nah, it doesn't generally bother me. The car corners well enough for commuting. Add lowering springs and a rear sway bar and 90% of the body roll is gone and now you can feel the limits of the narrow tire. Most of the time this is fine unless you like hitting corners fast all the time. If so then 17s or 18s is the perfect upgrade. Just be prepared to lose 4-8mpg. If you don't drive many miles per year then who cares. If, like me, you drive closer to 30,000/yr then the mpg loss is harder to swallow.

 

I have never intend into specific observe about MPG on my G3. I just look on the display,that's all. Never count actual MPG. Regardless how many MPG i got, im still very happy. (I just sold my Mbz ML 350 that gives me only 14-16 MPG....). I used to fill my gas once a week $60 (from my ML 350), now i just need to fill $15 on my G3.Btw, im still using 91 instead 87 which is $4.65/gallon..:cheer2:

 

And that is a damn good feeling! :rockon:

 

I have yet to see an 'Aero' package that claimed to be more aerodynamic than stock. In theory, keeping air out from under the car is useful, but the Gen 3 Prius is already pretty aerodynamic under there.

Ditching the outside mirrors and antenna may be the only simple mods.

 

You damn right. I have put over 3000 miles on my car, and yet its not even 1 month since i bought.... I go out of town every weekend, and visiting my parents (150 miles away) now....:rockon: