Luxury taxes on cars were nothing more than a sop to the domestic manufacturers who were producing a sup-par product with low build quality who eventually left anyway. We have no industry to protect, and 'luxury taxes' are just an attempt at double taxation unless you are spending your money in a state-approved fashion - you know, income you've already paid tax on when you've earned it.
It would be a consumption tax on discretionary spending - like GST is, but not in this case not in a regressive way. Instead pay less income tax, then no GST if you buy a Toyota - but if you decide you need a Lexus instead, that will cost you more. Perhaps you decide to invest that money instead and buy the cheaper car, or maybe you want the nicer car, and hey - you're lucky and successful and you can, but you pay a little more because you're in a position of privilege with a choice.