people will run out and buy cars before the tax hits - that's human nature, and that's the way consumers will behave. it happened in California when Davis went with his auto tax. it happened when there was a luxury tax on boats also.
You are trying to compare apples and oranges.
A] This is not an additional tax.
B] When the new system goes into effect, you will have all of the old federal deductions back in your pocket. That will mean anywhere from hundreds to thousands more dollars per month in your wallet - not the government's.
C] Items such as automobiles that were in dealer inventory prior to the change in taxes will be tax exempt. Vehicles coming in after that date will be cheaper because the cost of embedded taxes are removed from the manufacturer and the dealer. Competition will assure that there is no price gouging and there are now, and still will be laws against price fixing and collusion.
The Luxury Tax was an abomination, no doubt. But that was an ADDED tax. This is not. It's a replacement. There may be some people who will delay a purchase temporarily, but from over a quarter of a century experience in the automobile business, I can guarantee you that dealers and manufacturers will be beating the drums to make sure that you understand what's going on with the change. Anyone who wasn't able to make a deal before, will suddenly be surprised at the change and the salespeople will be on the phone. I'll give it a month to adjust to any uncertainty. That's it -- one month. And then look out or you'll get run over.