Do not hire cars from the Sixt in Keflavik.
They will not inspect the car unless you ask them two. The cars a all beaten up with scratches and small dings, when you take it back even if you did drag the guy out to inspect the car he wont have marked all the damage and they will try to charge you 1000 euros to repair a scratches that were already there on a car that hasn't seen the inside of a repair shop in years!!!
This not only happened to me but the woman in the line ahead of me. So for my visit to return my car that was a 100% hit rate for Keflavik Sixt.
I have complained to the Icelandic Tourist Board and Consumer Affairs, the local police and disputed the claim with my credit card. I suggest anyone else similarly affected does the same, I can see there are quite a few people posting here who were.