A vehicle includes a bulkhead and an airbag inflatable to an inflated position. The airbag includes a forward-facing panel mounted to the bulkhead and a rearward-facing panel opposite the forward-facing panel. Then airbag in the inflated position has a left extension and a right extension extending from the rearward-facing panel, and an intermediate extension sandwiched between the left extension and the right extension. The intermediate extension extends from the rearward-facing panel farther than the left and right extensions. During a vehicle impact, the momentum of the occupant may move the occupant towards the airbag. The airbag may absorb energy from the head and knees of the occupant.