The STI has never been a particularly efficient vehicle and the new one is no different. Even with a 2.5-liter engine, the boost is turned up to crank out 305 hp and 290 lb-ft of torque. A lot of fuel is required to generate this kind of grunt and combined with short gearing, the STI is rated at a mere 17 MPG in the city and 23 MPG on the highway. After a week of mixed driving that included plenty of spirited romps, we average 19.6 mpg.
