Either on line or you can figure it up yourself by filling the tank, writing down the mileage and how many litres of petrol you've put in the car when you fill it up, then drive it until you have to fill it up again, then write everything down again. Then just divide your gallons used by the mileage you've accrued to figure up your gas mileage.
Ok then i'm just lazy at times. So your car has a quarter tank of fuel then? That should last a few days unless you plan on driving all over creation tomorrow.
No, i'm off tomorrow. Remember, it's saturday tomorrow. Besides, i've got to get my caribbean red transplanted into a larger pot. I've been putting it off way too long and she's suffering because of me. I'm such a jerk.