I fill my tank full, travel approx 300km to 350km this is when tank is quarter full (as seen on the gauge) so I go and fill up my car roughly 35lt which means I had 15-20 lt fuel in the car. I have to fill up my car once it has traveled between 300km-350kms if I don't then my car starts to Jerk between 30-45kmph speed. I have taken to 3 mechanics but nobody can find out what is wrong. few days earlier Hyundai mechanic did a diagnostic and said there is something wrong with the value body and transmission and I will have to get the replaced/repaid which would cost me around $4000 , but he was unable to guarantee that my above problem will be resolved. I am stressing that there could be 2 different issues one with the transmission and another with fuel management system. I have no clue about cars and I have done everything I can do to fig. out this jerking problem but nobody seems to give me any answers?
can anyone please share some knowledge that why my car only jerking (travel speed 30-45kmph) and (when tank quarter full) to avoid this I have now started to fill my car once its half tank. Thank you for your help