Sorry, but I don't have the numbers in kpl, but I do have them in mpg. The 280SEL gets about 15 in the city and tops off at 20 or so on the highway. The 280SEL is quite a chunk of weight for that motor to pull.
You may want to delete this from the tech help section and post it in the open discussion forum.
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K