A key aspect to Cadillac’s resurgence is something most consumers overlook: lightweight construction; serving the dual purpose of procuring better fuel economy and reaping improved handling. Take the all-new 2017 XT5, for example. It’s nearly 300 pounds lighter than the SRX it replaces yet offers more than 3” of increased rear-seat legroom on a wheelbase that’s 2” longer. That packaging efficiency is achieved in a vehicle with an overall length, …