Poor Mileage

Good looking, excellent road grip, excellent handling but mileage on highways is very poor. I drove my car for more than 600 km but the mileage was only 18km/Lit. Really disappointing as they are claiming the mileage of 28 km/lit. I purchased this vehicle just for the mileage only. Now it is very disappointing. If I had known this earlier I would have gone for some other vehicle as there are many good options in this price range.