2002
wrx
stock td04
up, dp, sti tmic, cbe
average 17 mpg all city
gst tune

 

My Old 2001 RS
2.5RS
NA
AEM SRI, CBE
26 MPG on Average
Mixed

My Old 2007 WRX
WRX
TD04
TBE, STi TMIC, Perrin Y Hose, Cobb AP
25 MPG on Average
Mixed
OTS Cobb Stage II Map

My Old 2004 STi
STi
Superzilla 49 Turbo
Cobb AP, TBE, Up-Pipe, JDM STi TMIC, 3" MAF, Injectors, Fuel Pump, MBC, etc.
16 MPG on Average
Mixed
EQ Tuning Protune @ 310WHP

My 2008 STi
STi
VF48
Cobb AP, Invidia DP,
19 MPG on Average with Mixed Driving, 24 long Highway Driving
OTS Cobb Stage II Map

 

2002 WRX
18G turbo
Sti Pink injectors
Walbro Fuel Pump
Turbo XS TMIC
Up pipe
Titek Catless Down pipe
Borla Hush TBE
GST TUNE/ V1 accessport

19-21 MPG mixed driving

 

2003 WRX
K&N Panel filter w/ Snorkel removed
Catless uppipe
Bosal divorced wastegate downpipe
Prodrive cat-delete pipe
Magnaflow custom catback
VF34
STi pink injectors
STi TMIC
GP Moto equal length headers
Lightweight crank pulley
Turbo inlet(silicone)
Walbro 255lph fuel pump
GM Boost Solenoid
Clark Turner Tune/V1 AP

Very low MPG.. I don't know exact, but my work is about 25 - 30 miles one way.. and it takes about 1/4 a day to and from work. But I drive 80+MPH, and I like boosting.. especially when I see other cars that look like they want to speed.

 

04 sti with helix TBE and snorkel delete
no tuning

19-20 MPG

mix city and freeway

 

update myself here

98 RS
ej255 td04
dp, intake
19-24 mpg
mostly street, some highway
FLI Protune

 

I'm due for an update as well. Maybe more of a conclusion to this experiment...

When I posted this thread, I was nearly stock on my 02 wagon, with the exception of a CBE and BOV (removed since then..). No tune, and getting roughly 23-25MPG on average.

I've since gone VF-43, STI TMIC, WRX BLUE injectors, and full TBE, with an EQ protune. I'm now averaging about 21-24 MPG.

A slight downward shift in MPG, but my driving style / habits have definitely changed..


As mentioned by several members, there probably isn't a direct correlation between turbo size and MPG, except for extreme cases involving huge turbos and, consequently, huge injectors.

There does, however, seem to be a correlation between Turbo size and driving style, and furthermore, driving style to MPG (hence an indirect correlation). It would only make sense that if you put in a bunch of money to upgrade your turbo, you'd want to drive harder..

This indirect correlation seems to hold true in every case mentioned above.



So, to conclude this thread (as rare as it is to do), I'd say "Myth Busted." That is to say there is no discernible difference in MPG when performing mild to moderate turbo upgrades. It all depends on the tuner, the type of driving (bumper-bumper commute vs. open highways), and most importantly, the driver's style.

If this thread has any future use at all, it would be a nice catalog of what MPG to expect based on your particular driving style and type of driving conditions that you could compare to other members.

 

LOL, thats changed