My secret.... I only do dealership shops around lunchtime. Hit it, make it stick, then quit.
I tell them I'm using my lunchbreak to shop and get a better feel for features, prices, rebates, promotions, etc...
I never state what time I have to be back (because it's flexible anyway) or that I'm in a rush, just that I'm on my lunch break, but.... I get some really streamlined, thorough presentations with no chit-chat. I guess they just assume that my lunch break is an hour like most people's and try to really drive home their presentations in under an hour.
I've seen people on here talking about dealership shops taking them 1 1/2-2 hours, but honestly, mine have never taken more than 45 minutes even with testdrive. My salespeople typically gloss over some of the features, offer a test-drive, I accept, and they go over the features more thoroughly during the testdrive.
Never go after "work hours" or they'll think you have all the time in the world.
------------------------------------------------
Plan the work. Work the plan.