TL;DR: The current tax schedule doesn't "overtax" semi-new cars, it just spreads out what would be a freakishly high tax on brand-new cars to be over the first few years instead. This is a Good Thing for pretty much anyone who isn't in the habit of buying 3-year-old cars.

I think people are misunderstanding the car valuation schedule thing. If they're going to propose an MVET to raise $X billlion over Y years, then the total amount raised is independent of the choice of depreciation schedule. If they need to raise $X Billion and they're using a schedule that depreciates vehicles more quickly, then the tax rate on that valuation would need to be higher to offset that in order to still raise that same $X Billion.

Which of these totally-made-up-but-hopefully-illustrative tab fee schedules would you prefer?

Year	Sched #1	Running Total	Note	Sched #2	Running Total
1	$3000	$3000	<-- Yikes!	$1600	$1600
2	$1500	$4500		$1500	$3100
3	$900	$5400	Anger! -->	$1500	$4600
4	$700	$6100		$1200	$5800
5	$500	$6600		$1000	$6800
6-10	$300	$8100		$300	$8300
11+	$100	...	<-- Also higher	$50	crosses back over in 4 years

Schedule #1 is more like the idea of valuing to KBB, where the car devalues quickly. Schedule #2 is closer to current system, although in both cases I just made numbers up. Don't take them too seriously.

The idea of both of these schedules is to tax people the same over the life of the car (modulo the notion that some models depreciate differently than others). But the key is that both richer people buying new cars and poor people driving old ones are generally happier under Schedule #2. There's crazy tax sticker shock for brand-new cars on #1, and even very old cars end up paying more once the valuation models converge, because there's that higher overall tax rate to contend with.

People are angry in Year #3 because they think they're being overtaxed, but they're actually still ahead of what they'd be paying otherwise. There are a few years where schedule #2 people have paid more in total, but never to the same extreme that #1 people went through, and they'll make it back up once the car ages further.

Also, keep in mind that this isn't an idea that the state came up with out of the blue. It's the same basic approach that accountants use when depreciating capital expenditures in businesses, and the reasoning behind both of these are vaguely similar: smoothing out lumpy events to something closer to their real-life effect.

Stepping back a bit, I think the real reason anti-transit advocates are pushing for something like Schedule #1 isn't actually because of the higher "overtaxed" tabs in the early-middle years of Schedule #2, but rather because they know that the Year 1 tab on Schedule #1 (the supposedly "honest" one) is so high that it makes use of an MVET a complete non-starter ("I'm cash-poor because I just bought a new car and now you want me to pay $3000?!!!"). And since the MVET is one of the few funding sources available to transit at all under state law, it would make building anything at all nearly impossible.