There is a problem with series hybrids. Turning a gas motor then making electricity then turning it back into motion with an electric motor is less efficicent then doing it with a gas motor in the first place. Series/Parallel like the Prius is the best for many uses. The Prius system is often looked at as a 'small car' solution but the power split device in the Prius as well as all of the rest of the systems could easily be scaled way up.

A series hybrid problem is mostly the batteries. You loose more then 30% when you put the power into the batteries and take it out again. Supercaps solve this problem (and the battery wear problem) but you loose the juice when it sits too long.

It's probably too early to accurately speculate on price since this is still only in evaluation mode, plus the cost uncertainties we all know about with lithium ion batteries in the near future, etc. But it does seem to me that this could potentially do a lot better than 10 to 20% improvement in fuel economy, just as in Nick's post. I see these kinds of vans used frequently for shuttles between a hotel and airport, for example. Plugging the van in during the time periods it was waiting to make the next run might extend the battery's range to cover most of the day, particularly where the hotel was within a few miles of the airport. In any case, a major manufacturer testing these systems is a great development. The wheels are rolling on this technology.

I agree, why hasn't anyone started offering solar panels as options to any electric vehicles? With most trips under the full range of the batteries, solar panels could provide most of, if not all, of the energy to recharge them, and they would be charging during the day, all day. Another thing that has been very disturbing is that why don't the manufactureres offer electric versions of the same cars that they currently produce? Most electric cars, look like toys. If you don't mind driving a toy, that's great, but some of need our vehicles for carying things (like groceries). Come'on motor manufacturers, give us real options!

There will probably be an interlock system that will prevent driving away while plugged in.

Unfortunatly solar panels on the roof of a car provide very little power. A typical electric or hybrid car can go 2-4 miles on 1kwa of energy. So if you put a 1000w aray on top of the a car it would cost $8000 or so and give you 2-4 miles of range more each hour it was in full sun. So yes it could add 20 miles of travel a day but there is no escaping the $8000 cost. If you drove very little and had a large battery it would work well but otherwise its quite expensive.

Secondly you could not fit a 1000w array on top of most cars, though you could fit it on the sprinter pictured above.

Two factors also working against you, the weight of the array added to the car and that the array is not properly positioned so a 1000w array would almost never produce 1000w.