Lud,
First, I think the idea is great.
Second, I totally agree with how you've got the '91-96 cars classified.
However, I would make some changes to your classification of the '97 and later cars.
On the '97-99, you've got:
$40,000 - $45,000 some '97s with very high miles and issues
$45,000 - $50,000 some '97s in medium condition or minor issues
$50,000 - $55,000 '97s with high miles, some later models with issues
$55,000 - $60,000 '97-99 with low to moderate miles
$60,000 - $65,000 '97-99 with very low miles and good condition
Your description of the '97 cars in the $45-50K category sounds better than that of the $50-55K category! Obviously, needs some tweaking.
Also, prices have dropped on the '00-01 cars, due to the drops in the '97-99 as well as the bargain prices on the '02. I have had two different people tell me that wholesalers are quoting $56-58K on an ultra-low mileage 2000, which means retail is in the low sixties, not the high sixties.
I would change these descriptions to the following:
$40,000 - $45,000 Moderate '95-'96 NSX-Ts, some '97s with very high miles and issues
$45,000 - $50,000 Very good condition and low mile '95-'96 NSX-Ts, some '97s with high miles or minor issues
$50,000 - $55,000 '97s with low to moderate miles, '98-99 with above-average miles or minor issues
$55,000 - $60,000 '98-99 with low to moderate miles, '00-01 with above-average miles or minor issues
$60,000 - $65,000 '00-01 with low miles and mint condition
HTH