The 2015 Mercedes-Benz GLA45 AMG arrives with the most powerful series-production four-cylinder engine in the world. How powerful? 355-hp and 332 lb.-ft. of torque, good for a 0-60 mph run of 4.8 seconds. That power is now routed through Mercedes' AMG 4MATIC four-wheel drive system, and while it's still effectively a front-wheel drive, it splits torque 50:50 when needed. A 7-speed DCT transmission promises speedy shifts, and launch control comes as standard. Pricing isn't yet available.