Disappointing Performance with Short of fuel efficiency & quality expectations

I bought the car in May, my experience has been disappointing. The company claims 20km/l fuel efficiency, but in reality, I'm getting only 12km/l, based on my actual driving. Over 12709 km, I've consumed 1059.69 liters of fuel, far from the expected mileage. Most of my driving is on highways(Delhi-Meerut Expressway), so I expected better fuel performance. Besides FUEL EFFICIENCY, I've faced another issue. The car makes a THUD Sound when crossing speed breakers and potholes from one side, which the company claims is normal. More concerning is the feeling of instability during extreme turns ( like u-turns), almost as if the tires could break out of the axle. Overall, I feel disappointed by the car's performance and the misleading online reviews. The tribe RXZ doesn't live up to its promises and is not recommended to others.