We'll admit, it feels like a typo whenever we write " 4 Series ," but if BMW is as insistent upon further breaking out its coupes and convertibles from its sedan ranges as we've been hearing, we'll just have to get used to it. The BMW 4 Series is expected to officially kick off when the two-door versions of the new 3 Series are launched, and our spies recently caught a prototype of the new droptop 4 testing in the rain.There's still lots of cladding under all that swirly paper, but we expect the 4er Convertible's design to mimic that of the new 3 Series, complete with the more squared off headlamps that pinch in toward the dual-kidney grille. Like the outgoing droptop, the 4 Series cabriolet will use a folding hardtop configuration, and engine choices will almost certainly be exactly the same as what's offered in the 3 Series sedan. (428i and 435i – weird.) An M version is also said to be in the cards.Look for the 4 Series range to debut sometime in 2012.