Hi, understand what you are saying but for two years i was returning 32 -35mpg and when towing on long runs ( 200 miles ) 28 mpg I know ! I was surprised . Mazda said that the SL 35 td should return these figures .... I have the old transfer box. I have been told that the difference between the G reg RR running gear Gearbox ect and the 300tdi running gear and box is so slight it would hardly make a difference ???? . Bottom end torque was and still is amazing, Pulling/ploughing my very low loaded trailer ( 2,200kg ) AND a loaded transit van and catering trailer through 50mt of mud earlier this year ( I was too lazy to unhitch ) 2nd gear low, diff lock . I am running on 265.75.16 off road tyres at 40psi when I tried much narrower tyres over 500 miles ...NO difference and almost got stuck. ! Would fuelling have this drastic drop ? I had it checked a while back after I used petrol and nothing could be found. Also it starts on the first crank even in this weather when standing for 4 days ...Thanks Pete