With current technology, mobile working has become a real trend. With wireless head-mounted displays we could soon even be using immersive working environments while commuting. However, it is unclear what such a virtual workplace will look like. In anticipation of autonomous cars, we investigate the use of VR in the rear seat of current cars. Given the limited space, how will interfaces make us productive, but also keep us aware of the essentials of our surroundings? In interviews with 11 commuters, they generally could imagine using VR in cars for working, but were concerned with their physical integrity while in VR. Two types of preferred working environments stuck out in the physical dimension and three information levels for rear-seat VR productivity emerged from our interviews: productivity, notification, and environment. We believe that the interview results and proposed information levels can inspire the UI structure of future ubiquitous productivity applications.