When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The only mod I have on my 2011 GT (6 speed with .373 gears) is an Airaid CAI. I get an average of 12.2 MPG but almost all of my driving is on city streets. I recently did a 125 mile highway trip and used the cruise control and kept speeds to 70 MPH. This netted 22 MPG on the highway.
2014 GT with 3.90's and getting 15-16 city. I do not baby it on take off, typically shifting 1-2 and 2-3 @3.5 -4k. Love the way it pulls and sounds with the Corsa's. These motors really like higher rpms.
My 14GT gets about 18-20 in the city and I have seen 27 on the highway a few times with an average of 24-25 on the highway. But I do have the 3.31 gears