I guess this is merely stating the obvious, but I get the same gas mileage on my 204K 300E. Just gotta love these W124 M103 cars. Probably some of the finest ever built.
With the A/C off I get similar gas milage in my 400E.
81 300 SD grey/palomino 168K miles
84 190E 2.3 black/grey 64K miles (wrecked)
85 190E 2.3 maroon/palomino 92K miles
88 300E desert red/palomino 204k miles
(made to look like a '94-95)
92 400E desert taupe/creme beige 120K miles
(converted to 94-95 E420 looks)