hydrocilator

Hi guys, new to the forum and new to diesel power :D I like the amount of info on here. I have been offered an 2000 Merc C220 CDI, low miler, presumably W202. Does anyone have an idea of what mpg I should be getting from this car? I do 100 motorway miles a day. I always liked the styling and shape of these cars so would really like the opportunity to drive one. Anyone with experience of this model like to point out any common faults for when I go to view the car?