Not that it's manufacturer recommended but you could try cleaning the injectors with something like Redex, it'll help reduce consumption a little. Ensure you aren't in sport mode as that'll burn extra fuel, so regular mode and easy does it on the gas peddle. If you observe your instant fuel consumption data on the dash you can monitor how your driving style is affecting things. Check how much junk you have in the boot, lighter goes further for less juice. Keep your oil topped up too, your cat will respond in kind. I suggest 'Castrol Edge Sport'. Everything is smooth and efficient on that stuff!