2013 Subaru Impreza WRX STI - Project Log - Page 32 - Fuel Economy, Hypermiling, EcoModding News and Forum

jedi_sol · 06-17-2015, 05:11 PM

Tesla model S parked next to me at work. I took a quick snap of the rear underbody. It turns out it has an inner sides skirt for the rear tire too!

Did a quick coast down test with inner side skirts. On the same stretch of highway on my daily commute, i accelerate down hill to 65mph to a constant point, coast until i hit 50mph, then I take a mental note of my location. When i get to work I measure the distance on google maps.

Coasting distance increased by 146.19 feet which calculates out to a 6.2% increase in coasting distance.

I also bought myself a new toy. A Cobb Accessport to dip my feet into ECU tuning

A stage 1 "off the shelf" tune from Cobb claims an extra 10hp and 15lb torque. I can definitely feel the difference in my butt dyno. However, the kicker is I don't see a penalty in MPG! My daily commute to work jumped up to 32mpg! Supposedly the stock tune from Subaru is horrible. Extra power, no mpg loss = cake tastes really good

Cobb also offers a "Economy Tune" as well. From what I've read on the Cobb website, it lowers the boost down to 8psi. I thought to myself, "well that doesn't seem that hard to do." But something else must be going on because the car still pulls slightly harder than stock tune, but now I can consistently hit mid 33mpg on my daily commute to work

Daily commute to work:
Stock tune = 30-31mpg
Stage 1 tune = 32mpg
Economy tune = 33mpg

When i find some more free time, i'll do a proper ABCABC test to test out more accurate mpg gains with the Stock tune, Stage 1 tune, and Economy tune.

wdb · 06-20-2015, 10:57 AM

Quote:

Originally Posted by jedi_sol

I also bought myself a new toy. A Cobb Accessport to dip my feet into ECU tuning

Wow, Cobb has come a long way. I have one of the older models on my 2005 STi and the fuel economy was worse with the Cobb tune.

jedi_sol · 06-22-2015, 07:05 PM

I re-did the inner side skirts by replacing it with 6mm thick coroplast, it's much more sturdier and less "wobbly" than 4mm coroplast. I also had the plastic store cut it for me so that the skirts came out straight and even (instead of crooked and janky) lol.

I also got around to installing the outer side skirts as well. Prepping for paint with black Plastidip. I decided to paint the oem side skirt as well for the purpose of blending in with the coroplast side skirt. Hopefully it will make the coroplast side skirt less noticeable.

My fiance hasn't noticed it yet

It's been really windy this weekend, so I couldn't test out the combined effectiveness of inner and out skirts. However, i do notice that wind noise has decreased a bit more.