Also, it's not theoretically, OR practically possible for a Mark X 2.5 to get such low figures. The 2.5L V6 in the Mark X is the same one used in the IS250's, which manages to give 23-24mpg, which translates to 12km/l. Now of course actual figures would be lower, but it's just to give you a little "food for thought" on what to expect with that engine.