Ground Sucking My Car

so i've been trying to change some stuff on the regular gridmap , but the terrain where the old mud used to be keeps sinking even after i change it , i've been trying all sorta stuff to get rid of it (none worked) , can anyone out there help me to stop this from happening ?

 

Well the mud usually makes the car sink a little bit right? So did you try altering the ground beneath it?

 

Eaten up by Gridmap