A knee airbag includes a front panel, a rear panel and first and second tethers. The first tether is between the panels and defines an outboard chamber. The second tether is between the panels and defines an inboard chamber. The tethers cooperatively define a center chamber. The chambers, in an inflated position, are substantially vertical and parallel. The inboard chamber is thinner than the other chambers. In the inflated position, the tethers respectively define first and second knee-receiving pockets.