Real stickler for the rules! Despite other car companies having no problem renting cars with only a US License, Sixt flat refused my rental without an International Driver's Permit. Big time buzz kill for the vacation. I appreciate that these are the rules in Estonia, but honestly this should have been made abundantly clear to me in the rental process. I shouldn't have to dig into the Terms and Conditions section to be certain I am good to rent a car when your website is more than happy to take my reservation and my money.