my first full month with the car, filled it up and zero'd the clock. at the end of the month now and clocked up 150 mile and its about to go onto the reserve. i havent been thrashing it. i admit occaisionally i have give the car boot. working out the mpg its done about 15-18mpg which is terrible

brakes are fine
tyre pressures are fine
its just had new plugs and a new pipercross panel filter
no other mods

any ideas ?