If this car has a genuine 66k on it, I would expect next to no wear on things like the steering wheel , seat bolsters, carpet around foot rest, gear knob and boot, handbrake leather, engine should look spotless and whole car mechanically flawless. If there is visible wear on any of the above, I call bullshit.
I bought my 33 gtst last year. The cluster showed 58k km and the seller was adamant it was genuine. I quickly looked the car over and pointed out to the owner some wear on some of the above items. I told him that based on that I would estimate the car had closer to 160k on it. Still fairly low for age. Long story short, I comp tested it and got 170psi across all pots and ended up buying the car for 10k incl rwc which is quite pricey for a 33 gtst. The previous owner had a complete history since he owned the car and receipts totalling over 13k for mostly cosmetics and maintenance items, mechanically was stock and in fantastic shape. The point is, I knew what i was buying and bought on condition rather than what the alleged kms where.
If the 33 your looking at is really that good then keep talking to the dealer and negotiate a better price. That has to be the highest priced 33 I have seen for a long time. If it doesnt work out, there is plenty of other 33's out there. My 2c. Good luck.