i know there has been a million threads before bout this but there is just so much it is hard to sift through everyhing and find what relates to my issue
ever since owing the car i have never had economy like others here suggest they get
i have a 3.5l auto and i average 14.5 to 15.5l per 100kms city
down to 14l to 14.5l per 100km mix of highway and city
and only ever as low as 13l per 100km
i am currently going to get a service done
i will be changing the spark plugs, ignition leads and dizzy cap
changing the o2 sensor and also getting a throttle body clean and my fuel injectors ultrasonically cleaned.
is there anything else i should look at????
i will also be changing my trans fluid as i am installing a transmission cooler... if the oil is really dirty should i get a full service done on the gearbox????

You do realise you have answered all your own questions? Just saying...

i know i was on the right track just not sure if i missed anything that might be a problem also..... incase this doesnt work....

Also pump your tyres up and clean out unwanted weight. just a couple of often overlooked points

Maybe also closely examine your driving style - you may find that you can alter your driving technique and greatly improve your economy. My TL gets around 8L/100km on long trips cruising at 100kph and 12l/100km in town on short runs. Admittedly I probably drive like a granny (I'm actually a great grandad) but keep to the speed limit so it ain't exactly sedate driving....just smooth driving.

Make sure you're running the right engine oil viscosity.