 Starting in 2012, the Tesla Model S offers their own patented height adjustable suspension as an option.Two goals are accomplished the long, low slung car can be raised to avoid road obstacles it also lowers at speed on the highway to improve aerodynamics.Height adjustable air suspensions are also equipped on some buses, mainly "low-floor" city buses or "kneeling buses", however in recent years some high floor charter/intercity buses have been equipped with this feature as well.