An airbag assembly with a reduced-cost knee airbag cushion and internal tethers can be formed from a single rectangular panel of material so that there is very little material waste. A pleat can be formed in a rear face so that the combination of tethers and pleat help the cushion deploy with favorable characteristics and adopt an arced shape when inflated. The cushion can have apertures for inserting an inflator with mounting stems partially within the cushion so that the mounting stems can be used to couple the cushion to an airbag housing. The assembly can also have a bag strap formed from a single piece of fabric that can wrap around a rolled and/or folded cushion. The assembly can also have a stabilizer strap that can be coupled to the cushion and to the airbag housing so that during deployment, the cushion does not skew or twist.