Nissan has developed a "zero-gravity" seats for the application of the 2013 Nissan Altima. Aimed to reduce the fatigue associated with long driving, the new seat design was conceptualized around the idea of supporting the occupants in weightless environment.
Nissan has been looking at the idea for quite some times, and for those auto-engineering savvy, you can check out the SAE papers about this, Development of New Driving Posture Focused on Biomechanical Loads and Evaluations of Physical Fatigue during Long-term Driving with new New Driving Posture.
To reduce the tiredness on the occupants muscle, the muscle need to be relaxed in somewhat relaxed body posture in weightless environment. To achieve this, a patented varying support level in lumbar, midback and shoulder to position the occupant's spine in its natural position. The seat reacts to the occupant's load by holding the occupants in the natural spine position. The so-called natural position was determined based on 14 points along the seatback from the pelvis to the upperback. By doing do, the target loading value to a set of occupant's shape, the seat structure including the foam stiffness and bolster location were designed.
The 2013 model year Altima is seat to be the first Nissan's production model to receive the technology. It will be eventually rolled out to all Nissan model. It seems that Nissan is one of the manufacturer that is very particular about the interior innovation. Sometimes in mid 90's Nissan introduced some kind of anti-bacterial technology for its Nissan March/Micra.