Havent had the car long yet so havent done much to it. Replaced factory wheels and tires with something that had some grip. The car comes with bicycle tires on it...seriously. Went from 215/45-17 on 7.5 inch rims to 235/45-17 on 8 inch wide rims...it looks better, handles better, and on one road trip I managed to eek out 36.9 mpg.
No ecomods yet...the factory has already done some really clever things with this car including killing the alternator during daytime driving when climbing a hill. Smart guys these subaru engineers.