I returned the car with tank full(actually little more the full),
had taken picture of the fuel meter while returning just as a precaution,
and yesterday i received a rental record which stated that i returned by car with 4/8 of the tank.
after 12 mins wait on the phone, the customer service person...said he would credit my card for the extra charges, which is good... but for you travelers please beware about this, and yes as a precaution take a picture...this is where our camera phones come in handy :)
wish you well