EV speed limit is a matter of changing the gear ratio on the planetary gears and providing enough current to overcome air drag which quadruples every time you double the speed. As far as claimed MPG go, there are few assumptions there:
1. electricity is cheaper than gas
2. no pollution from driving the car itself and there are many ways to produce electricity without pollution as well like hydroelectric, wind, solar panels and nuclear reactors. Even coal or gas fired commercial power plant is easier to cleanup, monitor and make more efficient.
3. Actually, believe it or not you can make electricity for free. You can install solar panels for your house and outside of initial investment the device is pretty much maintenance free. All extra electricity you can sell to the power grid to offset initial costs and there was a time where government incentives and tax breaks would even offset initial cost of building such panel or pay for itself in rather short time. And how do I know all this? Because my brother is working for small company doing such installations and trust me, some people made very well in long term by doing it. Of course, the more people take advantage of those tax breaks, the less incentives will be available.
It would be very difficult to calculate cost of electricity anyway, because prices vary widely depending on your location or even time of day, but yes, you're right there will be some additional cost for recharging batteries, but then price is not everything, otherwise everybody would be driving $10k econo box, everybody would be buying used car and most luxury car companies from Acura, BMW, Lexus, Mercedes, Jaguar, Porsche etc etc would be long out of business.

Pete4 — The actual portion of the NiMH battery's capacity that is used is more like 40% to 80% of full capacity. (This is based on numbers in a Toyota patent, and on what I have read elsewhere.) In any event, it's much less than full capacity. You're right about the reasons for this; it's to prolong battery life. The problem with current LiIon batteries is that, although they hold about twice the charge of NiMH batteries (per weight and per volume, I believe), they must be restricted to about half the usable range of current NiMH batteries in order to get the same number of charge/discharge cycles. This means that you're back to square one — no increased usable capacity!

Stan

Pete4,

I am actually considering installing solar for my house. Seriously, I am.

Can you please have your brother send me all of his free solar panels? Just kidding there. I think we both realize that solar panels aren't free.

I am trying to understand this better. Please help me out. My understanding was that the Prius and TCH use the range from 60% SOC to 90% SOC in normal operations. So that is 30% of full rated capacity. Are you saying that Lion would use 15% of the rated full capacity? If so, then I agree there is no net gain.

My memory is failing, so I'm not sure what exact range of SOC (State Of Charge) is used in Toyota cars at the moment, but yes, if Li-ion batteries need to have even smaller operating range to last long enough, then it would make no sense to use them because the double of capacity of Lithium, if used at half the SOC range would have exactly the same usable power output as current NIMH. The only way around that would be to make them really cheap, to the point of being wear part like tires and replace them on regular basis and using full capacity. Maybe we do need some radical development in battery chemistry after all or some totally new technology, like nanotube based super capacitors. One thing I'm sure, it takes long time to develop any new technology and it's a good thing finally companies are working on it, but it doesn't look like my TCH will be obsolete any time soon and that few miles range plug-in hybrid won't help much on my 30 mile one way commute.

Speaking of Prius, it's 40 - 80%.
http://privatenrg.com/#Full_SOC

Ken@Japan

chris_h — Yes, I'm saying that, from what I've read, the LiIon battery would have to use just half the charge fraction that a comparable NiMH battery could use. Like ken1784, I think the TCH's usable battery range (of 40%) is something like 40 - 80% of full charge. A comparable LiIon's usable range (of 20%) would then be something like 50 - 70% of its full charge.

Stan

Without the "ICE" running , batteries will have to supply heat in winter . Will the usefull range be crippled ? Secondly if the ice must run to supply heat in winter it might as well be charging the batteries and be used for power > full circle to what we have now .

Thanks. I understand now.

But this info makes me wonder if TCH's correlation of SOC to battery icon level is the same with the prius. I notice that the battery icon in my TCH is never full. The most I've seen is up to the 7th bar and even if it does it only stays there only for a short while. Also, it does not ever get below the second bar. I witness it again today when the car was in park with AC and audio off. The level eventually dropped to the second bar where ICE kicks on. Is everyone with a TCH seeing the same behavior? If so, then the functional range of SOC in a TCH is more like 50-70%.

Mine goes down to 2 bars minimum and when it reaches 2 bars it's a matter of seconds, maybe minute or 2 even with the car pretty much dormant, with no AC, not moving at all, before ICE will kick in. I'm not sure about the top, usually it happens when I'm driving at higher speed, often downhill, so I don't have much time to look at the screen, but it may be as well stopping one bar before top.
Question to Ken: is this graph for original Prius, or second generation? And is there a difference?
I read some more about usable SOC and I get conflicting numbers, from as little as 30% range to 40 % of total capacity.
Looking at standard NIMH discharge cycle one thing is obvious: it would be very difficult to predict SOC at any moment by reading it's voltage and it's the only simple way to do so. NIMH cell will drop of voltage very quickly being discharged from full, then it will level off and stay almost level for most of it's discharge time and then it will drop off very quickly to zero charge at the very end. That's probably main reason why ICE will stay on and keep charging battery to full sometimes, to recalibrate computer and then track SOC by calculating how much energy was charged and discharged, instead of just measuring voltage. That would solve the problem of voltage changing due to temperature and age of the pack.