It's a unique take on the variable compression ratio engine that has been in development for about 20 years or so. The thing that remains to be seen is the reliability of the system, as well as the overall effect that it has on reciprocating mass.
A bit off the subject, but one of the fundamental things to think about is just what powers a car. At it's essence, it is energy. Gasoline, Electricity, hydrogen, compressed air, a clock spring, etc. are all forms of energy storage. However we choose to power the cars of the future it will always require energy. The ultimate question then becomes what is the most efficient storage medium for that energy once it is produced. Efficiency is not only about power output, but about weight and size as well. To me, batteries are not an efficient medium for storage as they sit now. They are very heavy and require lots of space, and are not cheap either. For instance, take the Tesla roadster. It is based on the Lotus Elise, but manages to weigh 1,000lbs more than it's gasoline counterpart (if memory serves). So, while it may be a supposedly green alternative, it is not a practical solution due to the effect weight has on vehicle dynamics-especially handling and braking. It does accelerate better than the Elise, but in every other metric it is inferior. Well... except for fuel cost. Then again, it costs 2-3x as much as the Elise, so you really don't save anything.
