500 HP Upgrade for the BMW 135i Coupe
29 Apr 2010, 07:55 UTC · By: Dan Mihalascu / The BMW 135i is the most powerful of the 1 Series range, with 306 horsepower squeezed out of a 3.0-liter biturbo straight-six cylinder engine. It’s as close as you can get to an M-model, at le...