For a brand long associated with quiet, effortless cruising, Lexus has built a surprisingly spirited side into its NX 450h+ plug-in hybrid SUV. A roughly 100-kilometer round trip from Seoul to Ganghwa Island in Incheon offered a chance to experience both personalities of the mid-size SUV — its calm, efficiency-focused character in city traffic and its sharper side once the road opened up. The NX 450h+ is Lexus’ first plug-in hybrid model based on the second-generation NX platform. It combines a 2.5-liter four-cylinder gasoline engine producing 185 horsepower with two electric motors for a combined system output of 307 horsepower. On paper, those numbers suggest a fairly aggressive SUV. Behind the wheel, however, the first impression is not speed but smoothness. Its 18.1-kilowatt-hour battery allows the NX 450h+ to travel up to 56 kilometers on electric power alone. In city traffic, switching to Eco mode made the SUV feel almost deliberately relaxed. The throttle response was gentle, while the quiet electric drivetrain took some of the strain out of frequent stop-and-go driving. The ch