Welcome to the forum!
I'd try to get a "reasonably confident" idea of your economy. Fill the tank only to the first click, reset the trip meter, drive it for 150-200km away then drive back and refill it AT THE SAME BOWSER. Note the km travelled down on the receipt.
Then use this formula: (litres used times 100) divided by (km travelled) to get your LPHK (litres per hundred kilometres).
Your car should sit somewhere around the 15-17LPHK mark if it's not heavily laden and driven moderately.
If it's not, you could pay attention to a range of areas:
* ECU Reset - unplug the battery negative lead, stomp the brake pedal then return the battery lead, drive the vehicle gently up to about 95km/h and sit there for a while then stop and turn the car off - reset complete.
* Spark plugs - dirty plugs will still fire, but not as well, draining power and impacting on your economy.
* 'Leaky' spark plug leads. If the whole spark isn't getting to the plug, the fuel will ignite but very poorly, leading to incomplete combustion and a lack of power. This is best seen at night. You can examine the leads and notice a greying around splits in the leads.
* Dirty air filter. Petrol engines need decent air flow and a blocked air filter will cause the motor to run richer, providing less power for the fuel burnt. Extreme cases will cause the exhaust to be black on heavy acceleration.
* Dirty or worn injectors - try throwing a bottle of injector cleaner in the tank before looking for someone to remove and examine them. Sticky injectors (lots of 'varnish') can cause clouds or puffs of white smoke from the exhaust when accelerating.
Good luck!
to the Nav family mate.
