The 2018 Buick Regal TourX is a muddy vehicle. Not just because it is aimed at the hiking boot-wearing active-lifestyle set that marketers covet. Buick would like to see its new tall(-ish) wagon, which shares a nameplate, powertrain, and interior with the Regal Sportback hatchback, covered in dirt with outdoorsy accoutrements strapped to its roof...