You're still caught up in the idea that the tax is based on the sales price or the actual value of the car. But it's not.

According to the law, it's based on the greater of that or the book value.

You have due process, because you can inform yourself what the tax on the car is going to be before you decide to buy it. Apparently you assumed it would be based on the sales prices - that's an understandable mistake, but still a mistake of assumption contrary to the law on your part.

Now in terms of the distinct subject of excise taxes on already purchased vehicles, or property assessments, yes, the value of something you already own can go up, and long with it the taxes due. But the appropriate government process can also simply change the tax rate.

To win, you're basically going to have to show in court that you are being unfairly singled out, rather than being subjected to a policy that is the same for everyone.