“Luxury” is a subjective concept. These are the sorts of philosophical musings I find myself contemplating as I observe Chinese automaker BYD’s latest product, unveiled last week at the Guangzhou Auto Show, called the Destroyer 05. Many would consider a Tesla Model 3 to be a luxury vehicle — even in spite of the company’s well-documented build quality inconsistencies — but might not hold the same opinion of a Ford F-150. Some F-150s are stripped down work trucks, sure, but others have diamond-quilted seats that can massage you, headliners made of suede and dashboards of leather. It walks like a...