The rear bumper of the Sienna is a joke tho. Im quite certain if i backed up into a flat wall - the liftgate and the "bumper cover" will hit it at the same time. Its almost completely flat back there. No room for error.Those plastic bumpers are not bumpers, but bumper covers. The real bumper is under the bumper cover. It is designed to absorb impacts. It is quite substantial. The bumper cover is just to make it look good and does fall away in the event of a collision. You should be able to see the bumper in the Sienna by opening the hood and looking down in front of the radiator.