2009 Scion xB, purchased with 145k miles a few months ago. I have no idea what normal is supposed to feel like with this car but my impression is that the ride is rougher than I would expect. It doesn’t take a terribly rough road surface for it to go “thump” and jar you around pretty well. Is this an indication my springs are weak? Or maybe my shocks are worn? Or both? How do I know which part I should replace first?