Iceland Car Rental-
From Google reviews:
Iceland Car Rental was a great company for my husband and I who spent 2 weeks renting a truck in Iceland. They were very honest when they didn't necessarily have to be. A day after we got the truck we discovered some damage that we hadn't noticed before, and so we thought someone had hit us in the parking lot, which we would have had to pay for if that was the case. However, when we called the company, they verified the damage had already been there and it was not our problem to cover. We really appreciated their integrity, plus our car gave us no problems, even on some rough roads where 4 wheel drive is required!