This caused me an issue with company usage, when the fleet management company tried to enforce a minimum of 4* NCAP rating on personal cars for company usage, with the A8 not being rated they decided I could no longer use it. Wasn't until I pointed out they had a number of the fleet for the board that they decided to use the A6 rating "as it was basically the same car" - I didn't argue.
My understanding is that to gain a rating they have to crash a few, which with the testing costs €€€ - given that the A8 doesn't sell in high numbers, just not worthwhile for Audi
