The reason you see inventory out there that's open to buy is because people got cold feet and walked away from their deal. They ordered the car and now when it's time to put up or shut up, they've folded. Either the dealer wants too much markup and/or the car is just too much of a financial commitment for them. Or the car was a "coverage unit" that they didn't want to just sell to the first customer on the wait list so it was dealer's choice on the spec.
Regardless of the reason for cars being unsold, the end result is the same - unsold inventory.
At the launch of a new car demand generally comes from two sources , those who want the car, and those who want the car and to be first on their block.
Once the initial flurry dies off the remaining demand is for those who want the car regardless of when it arrives.
Let's look at competitors sales Aug YTD 2016
NSX - 45
Ferrari -all models 1600
Lamborghini -all models 726
Audi R8 - 446
Porsche 911 -all models 6582
GT-R 455
Total 10309
If we eliminate regular 911's and non 458/488 Ferrari's perhaps we're down to 650 Porsche's and 800 Ferrari's. (Hot Honda will know these numbers better than I)
So the total NSX competitive market segment may be about 3122 units in 8 months or say about 4700-4800 annually.
Honda is attempting to add 700-800 cars to this market segment.
It doesn't sound like many but it appears to be a significant volume in a very small market segment.
I would have thought Honda would first and foremost want firm sales to customers (not dealers) through the first model year to ensure a successful launch of a new halo car.
No unsold inventory, exclusive car, hard to find etc. etc.
That might mean 750-850 firm sales to allow for inevitable cancellations etc.
If we use your number of 90 cars made YTD, then between Honda and their dealerships they've got around 25 +/- unsold or over 25 % of production so far.
Don't think the dealerships will get the premium they're asking for and I hope won't be discounting unsold cars.
The only saving grace so far has been below-proforma factory production.
If Honda is serious about not having unsold NSX's then I think they need to ship only cars sold to an end customer in North America, then divert production to Europe and Japan.
If they don't take action soon they'll be looking at a plant curtailment over the winter