Luke

So i have had the brakes checked and my trusted mot garage put the Jazz on their rolling road to check for brakes binding and tyre state. It all came back clear. I have noticed if i take the car on the motorway, the mpg rises steadily and i can get up to 60 mpg. But goes back to a sorry 26- 28 mpg around town. Looking at this from another angle, the display shows 260 miles when tank is full and i think there is something wrong right there as that is way too low. Anyway both trip meters are set to zero. I only get 192 miles before the low fuel warning light comes on. A full tank costs me £40 -£45 every fortnight. My Golf Mk5 1.6 FSI lasts a whole month on on £50 Shell V Power. I am now thinking spark plugs and fuel filter both of which are a nightmare to change on this car. Other than that the car is very quiet and smooth. No misfire's etc but i notice the fan comes on and off a lot. I am also looking to change the oil but still trying to find which one is most suitable. This is driving me bonkers.

Honda Jazz EX CVT 2012. Display shows 26.9 mpg whereas if i remember correctly, the car should be doing 40mpg officially and unofficially, 35mpg around town. Only had the car for about a month. Car has done 36k with full Honda service history. Car was serviced in March this year but i checked the air filter anyway and its looks like new. Also checked tyre pressures and coolant & oil level and mass air flow sensor. It has been bitterly cold but will be surprised if mpg falls this low due to this. I can't think of anything else except the brakes binding. I even put a half tank Shell V power but no real difference. Car is mainly used for local driving. Any suggestions please.