My acura has been draining gas a lot and I have no idea what the problem is.

I did an oil change, changed the filters and spark plugs, but it only runs to around 320-340kms from a full tank.

During summer i never did use the ac and it ran to about 350-360kms, but now not so much.

Anyone know what the problem might be?

Wiring? something wrong with engine??? im not a car person so any ideas will help!