Tiago and it's issues

The Tiago overall is a nice car. However there are jerking issues with this car which unfortunately the company cannot rectify. The mileage on the car isn't brilliant either. The company states 23+ however after 5,800 KM's I do not get a mileage of more than 13 KM's To a litre. The people in the company say I'll have to wait till 15,000 KM's. However I really don't think that's the case. Built quality and fit and finish is still questionable.