The front end looks like a Lotus Seven’s might, if the minimalist roadster had been designed in 2015. The back resembles the south end of a warthog—muscular but ugly as a burnt stump. Inside you go then, stepping over the side rails and wriggling into an all-weather bucket seat, Formula Atlantic-style. Pull your helmet on, because this is technically a motorcycle. Now punch the glowing red start button, and the Polaris Slingshot thrums like a … 2.4-liter GM Ecotec four-banger?