IOW, only works if dealer is honest.
VW has 2 dealers in my region. Want a TDI Jetta with a manual transmission? Let the games begin -- they get 3 a month and the sales manager won't let it out the door for a good price.
Toyota used to have supply constraints for certain Camry models (some trims were made in Japan exclusively a few years ago). Want one of those? Good luck -- my dad had the guy demand a deposit to be on a waiting list, or take a lousy deal on one of the other trims.
Another thing that happens is that dealers need to trade with other dealers for specific cars. Sometimes these deals fall through, and the dealer who promised you a car is actually being honest -- he doesn't have it for reasons out of his control.
Interesting note: Be very careful about believing a dealer's website or phone description of a car as a "manual." We ran into multiple dealerships that misidentified paddle shift or "manumatic"/"tiptronic" cars as manuals.
He ended up with an RX-8, but that's an entirely different set of stories... :)
If the supply of a certain good is constrained, then obviously the value goes up. Simply being able to purchase one is a good price by definition.
The only correct response to such a situation is: "I will tell everyone I know about your tactics, and go with the dealer that was shooting straight."
Then execute on exactly that plan.
VINs can be decoded to exact colors/features for most makes/models.
In other words, go to another dealer.
Also, an interesting aside, there's a limited inventory in any given geographic region, so if you match your desire list up with a given VIN, they're usually quoting you on the same inventory item.
As others have said, this doesn't work for all cars. For less mainstream / luxur-ish cars, there won't be too many dealerships in 100 mi radius that carry what you want. At best you'd get a response that MSRP is this and that, please come in and we'll talk about discounts.