Most customers (80%) prefer the single padded seatbase model. Less padding means better and more controlled support to the pelvis and spine from the formed, shaped frame of the Backfriend. We do not (as a general rule) recommend using the double padded models in cars. With the extra height, some users can lock themselves against the roof! If you find the single padded version a little firm then a set of the real wool fleece covers make a world of difference offering optimum pressure dispersion without reducing the support from the frame of the backrest and seatbase parts.