So I just attended a FD class 16 hrs on Hybrids from a master tech that debunk a ton of false info.
http://www.mgstech.net/index.html
Long and short GM did drop the ball with the EV1 had GM developed this tech further they would have been hands down the industry leader. Now as I understand it when the Volts hits the market it will already be dated and the Nissan Leaf will be the next gen hybrid.
As it stand there are two type of true Hybrid technology exist Honda's and Toyota's
1) Honda's is very inexpensive and easy to build, but not as efficient.
2) Toyota is the industry leader and 90% of the car manufactures pay royalties to them. Such as Ford, Nissan, etc.
I'm not a expert, but spent allot of time talking with the instructor after class and he knows his S. He maybe a little bias toward hybrid, but did shoot me the strait poop on the were the market is going. The Volt battery will be it's weak point due to charge cycle life. The Volt is more of a true electric and uses the engine as a charger, but runs off the battery. If the battery life expires then it only has the ability to limp home. The Toyota battery does not care if it's has a full charge or not ( its always in a state of flux) and if it goes bad the car will still function and just become less efficient. Even if the battery does need changing he said it's about $2500 with parts and labor. He said some of the first gen Toyota had some issues, but the second gen and third gen will do 400K plus with no issue.
With all this said I'm still looking forward to the Volt, but the instructor did bring up food for thought. The EV1 technology was proven and just needed to be refined back in 1995 Toyota took this idea and developed it, marketed it, and now GM has to play catch-up that's the real shame in all of this.