Amid the onslaught of production SUVs launched at this year’s LA Auto Show, there were a couple supercars that also made their debut. BMW and Chevrolet launched drop-top versions of their halo cars: an i8 Roadster and a Corvette ZR1...

BMW in March finally confirmed plans to add a convertible version of its i8 plug-in hybrid sports car, having first previewed it in concept form as far back as the 2012 New York auto show.Sales of the i8 convertible, which...