A luxury sedan is something that should be a rolling oasis amidst the desert of daily commuting. Sure, some people will look upon your ride as irrational exuberance, but you earned the right to roll in style. Luxury sedans in this universe are also at the leading edge of development. Advances in safety, performance and convenience start at this level and trickle down to the hoi polloi. Here’s a snapshot of what’s coming and what automakers’ imaginations have produced, starting with the most recently unveiled.