The 2018 Subaru WRX STI is available as a 4-door, 5-seat sedan. Starting at $36,095, the 2018 Subaru WRX STI Base is powered by a 2.5L, 4-cylinder engine mated to a manual transmission that returns an EPA estimated 16-mpg in the city and 22-mpg on the highway. The top of the line 2018 Subaru WRX STI Limited w/Lip, priced at $40,895, is powered by a 2.5L, 4-cylinder engine mated to a manual transmission that returns an EPA estimated 16-mpg in the city and 22-mpg on the highway.