Strange Vehicle behavior on Spline

Hi people, I’m making a Car Game and on the third-person template floor, the vehicle works fine but on spline meshes created on the landscape, the car behaves differently. At some points in splines, friction is more, and at some points, friction is less. However, the is no Physical material applied to the landscape, material used on spline meshes and the same goes for third person template floor. I don’t understand why the vehicle is smooth on third person template map and behaves differently on splines. I’m using a paid plugin from Unreal Marketplace for vehicles, it is called Advance Vehicle System.
Can someone please help me to sort this out?
Thank You.