One of the unpredictable parts about being an automobile writer in Colorado is the ebb and flow of available vehicles and brands for our drives, as you’ve probably noticed in this column over the years. As a result, it’s been a long, long time since I’ve seen or driven any Cadillac products, and both Germany’s BMW and Mercedes have also become more rare, though Audi happily reasserted its presence. From Japan, Lexus is still plentiful, but Infin…