From a recent purchase on a used vehicle at the dealer, I have to say that an alternative to the 1/2 hour before closing tactic, would be to do something similar to what happened to me quite by accident (I didn't know about the 1/2 hour tactic until I read your website, but the effect was just the same).

Went into the dealer with my two kids, looked at a few cars, went for a few test drives, then went into the "shop" where I then experienced the salesman doing the pigeon on me a bit, but from what I can tell it still wasn't too bad of a deal, at least I think....
Next, they escorted me to the "finance manager" office, where they went on this big spiel about aftermarket insurance, undercoating, etc. I was hesitant, and they saw that in my behaviour..., so the manager (one cool salesman) played the concerned parent card on me with "...you don't want the car to break down on you with these kids, and no factory warranty left, blah, blah, blah" Well, he almost had me with my parenting instincts....
Just then, my kids starting acting up, jumping on the seats in his office, screaming, laughing, and being really loud (they had enough of the 2 hours out in the car dealer and decided to vent some pent up energy). The finance manger was still trying to persuade me into buying the add-ons, but he couldn't get a complete sentence in edgewise....(all the "Dad! I'm hungry....Dad, I'm thirsty...Dad! Are we done yet! I want to go home")

Needless to say, I ended up saying something like "Ok! I got to get these kids home already...Can I just sign this thing now and think about the extended warranty and the undercoating stuff and get back to you later?...." He couldn't push the paper in front of me fast enough. So, ten minutes later, contract read and signed, and kids still screaming as loud as they could, I ended up with no add-on aftermarket items on my car at all.

So, the applied lesson of the story...Before you go car shopping, Tell your kids that you need to play a game, and it just happens to be at the car dealership where they just LOVE to play kids' games. You have to be on your best behaviour, of course, but then when I give you "the signal", whine as much and as loud as you can until I give you the secret "stop" signal. The prize for the most awesome family whining? Slurpees for everyone!

that is the best one i heard in a long time. usually the finance mngr either is single or has kids he is trying to avoid. lol good idea. I think i will bring my grandkids next time.