On this episode of Ignition, Carlos Lago tests the latest generation of the perennial rally car favorite: The 2015 Subaru WRX STI. Much like the new WRX, this STI has an entirely new and significantly stiffer body structure, but unlike the WRX, it still uses the same 305 horsepower 2.5-liter turbocharged flat-four that's powered the car since 2008. Our introduction to the car occurs at the press launch at Mazda Raceway Laguna Seca. From there, we test the STI to see the performance improvements and drive it on one of our favorite mountain roads. How does the new STI stack up? Stay tuned to find out.