Mazda 3 2.2 185 diesel MPG issues
 

Hi I recently bought a 2009 mazda 3 185 2.2 mzr with 85,000 miles on its pretty clean and a nice car to drive. However the MPG is all over the place sometime struggling to get 30 mpg, The dpf is fine and isnt regening, turbo seems happy, its quiet and no weird sounds, runs nice and no weird issues. theres no smoke out the exhaust atall, I dont think theres any holes in the intakes or intercooler. just wondering if anyone else has had any similar issues and if so what did they find was the cause?
Many Thanks