If you read no further, my strong recommendation is that you NOT rent a car from OK Car Rental in Mykonos. If I had to do it again, I'd rent from Avis or Budget, both of which rent on the Island
In August 2011, I rented a car from OK Car Rental in Mykonos. I used OK because it was listed on our hotel's (the San Marco) website. The car was delivered to the hotel at 4:00 PM. I used it the first night to drive my family into town for dinner. I tried cleaning the dirty windshield but the wipers were worn and simply streaked the windshield with dirty water making it more difficult to see. Driving on the windy, narrow and unlit roads in Mykonos is difficult enough so a dirty windshield makes driving there dangerous. The next morning, on the way to the beach I first dropped by OK to have them change the wipers. I was surprised to hear from the manager that they didn't stock wipers. He told me he'd order them and that I could come by later in the day to have them changed. He then told me the car is new. I responded that it might be "new" but that doesn't change the fact that the wipers are worn and the seat back lever for the driver seat was broken and I couldn't adjust the seat. He said let me try the wipers and, as I told him before, they streaked the windows even when he tried them. When he said he didn't have wiper blades I asked if he could switch the wipers from another similar car sitting in his lot but he said that he wouldn't. At this point I was getting nowhere and told him that I'd return later (as he suggested) to have the blades changed. He then told me that he wouldn't have the wiper blades until the next day, thus, he was lying to me earlier. By now, I was completely frustrated especially having been lied to and told him to just get out of the car and I would go to the beach. He became very angry and told me not to talk to him that way, "that he's not our peasant" and then that he was taking the car back. When I said I already had paid for the car he said he didn't care and started driving off with my arm through the driver's side window. He then continued with his angry tone and threatened to "chop my head off." He demanded that my family get out of the car with all our things leaving us stranded even though I had paid for the car in full for three days.
At this point my friend, who had also rented a car from OK came by and the manager started yelling at him also. It was only after I had to apologize to him, repeatedly (I guess for getting angry when he lied to me) that he relented and returned to me the car I had already paid for in full.
Finally the car was delivered to me with virtually no gas. The gauge showed one blinking bar. I was told that was how it was returned by the previous renter but for whatever reason OK Rental did not add any gas before delivering the car to my hotel. I somehow made it to the nearest gas station, @ 5 miles away, and put in 10 euros of gas. Over the next three days the gas gauge, rather than showing fewer bars as the gas was used actually showed more bars even though I didn't add any more gas. My friend, who rented a similar car, had a similar malfunction in his gas gauge. When he tried to add gas, 12 euros worth, the gauge didn't move. As a result, OK tacked on an additional charge of 10 euros for gas. Thus, even though my friend and I drove similar cars for three days and drove with our families the exact same routes, he ended up paying 22 euros in gas while I paid 10 euros. All in all, we had a very negative experience with OK and I doubt that we would have the same experience with a more established and reputable company. Stay away from OK Rental in Mykonos.