A new BMW 4-Series variant has just been caught testing on the roads.As you may have already heard (or read on CarBuzz), the BMW 3-Series sedan will spawn both coupe and convertible variants and that will be badged as the 4-Series.And now our spy photographers braved the cold and the rain to capture the 2013 4-Series convertible testing on the road.The new convertible will feature a folding hardtop, just like the current model. Engine options should be the same ones found in the 3-Series sedan, so there are no real surprises there.The engines include BMW\'s new turbocharged 2.0-liter 4-cylinder which puts out a steady 240hp and 260lb-ft of torque, both numbers are a nice upgrade from the previous 328i\'s 3.0-liter inline 6-cylinder powerplant. There will also be a turbocharged 3.0-liter inline 6-cylinder engine that produces the same 300hp and 300lb-ft of torque.BMW will also be producing M versions of both the coupe and convertible, but those won\'t launch until about a year after the base cars debut.