We their production chassis very soon. It is quite likely that they will have an electric version and a hybrid version. This fourth version will be a bit larger and slightly heavier - but the electric version gets about 245MPGe which is more than 2X as efficient as the 102MPGe 250cc turbo X-Prize car; even though the electric version weighs 1140 pounds.
Their target price is $20K, by the way. You should watch the video of Oliver Kuttner at Green@Google - he goes into a LOT of detail about production issues and how they will keep the weight down to a minimum: