Have been using Diesel Kleen here in Florida and am trying to max out mpg. Had a 240D in the eighties which got a steady 28mpg around town and 36 highway. Thought I'd get at least 26-28 around town with this straight six diesel but still only 23 to 24. Is it the right foot penalty or what?

No leaks, additives moderately, get black exhaust at end of gear wind-up when I do use wot, use cruise (@77mph on highways and 50 to 55 locally), any ideas or is this good. Was looking forward to 32+mpg on open road and haven't seen it yet. Thanks, Rick