“Hybrids have the following advantages over traditional cars:”
The REAL problem...
Once out of warranty, the ONLY place they can still be serviced is the dealer. There is a real reason 75% of Hybrid buyers will not buy another one. The cost of ownership doesn’t justify the added costs at anything less than $6-7 gas.
Battery replacement is the real issue, and costs around $2,200. Without it, all you are buying is a 1.5L-1.8L under-powered compact car.
Braking issues related to the computer control for battery recharging have become a HUGE issue, as well. Other Computer Control problems seem to become huge issues on the Prius after they go out of warranty as well.
That's the fate of all high-tech gadgets. Can anyone but Apple fix your iPhone, for example?
The reason is that we are moving toward (or are already with) proprietary technologies. I had to throw an LCD TV out that failed (ViewSonic) even though I have the skill to repair it... if only I had the parts and the technical documentation on how to do it. Most of the stuff out there comes with no such documentation, and once it fails your only resort is the manufacturer. As a simple proof, try to repair an LED alarm clock with burned out segments. Those LEDs are nearly custom made, in Asia, and they ship them here only in finished devices. [This is a real example; some older HP test equipment uses those LEDs and it's tough to find spare parts.]
The time of carburetor cars is long gone, chased away by many reasons, among which are government requirements on emissions. You are already not allowed to mess with parameters of the engine control unit in your car, even if you know what you are doing (about 100% of the population do not; those who do are the rounding error.)
But it must be said that Toyota has a nice program where you can either subscribe to access to all their technical information (for a yearly fee, if you are a garage) or you can buy access for 1 day for something like $10. Anyone can buy access for 24 hours and download as much as his Internet connection allows.
Battery replacement is the real issue, and costs around $2,200.
NiMH batteries for Prius and like hybrids, as practice shows, are very reliable. Barring random factory defects, they actually work for the guaranteed period of time.
You probably noticed that in my list I haven't really mentioned savings on fuel. This is because, just as you say, it is far from obvious if you save or lose money on that deal. We do not know if a war breaks out in Persian Gulf tomorrow and gas prices go through the roof; or perhaps Obama loses his programming and allows unlimited drilling and pipelines and all, crashing the oil prices. Guessing that is pointless, and so is investing money into such a thing. My list contains only tangible advantages that are real from the first day of owning the car. It is up to each person individually to tell if they justify the higher price of a hybrid.
I do not know when or if any computer control issues with hybrids will show up. But I am an engineer who works with exactly such computers (embedded systems) for a very long time, so I do not think that anything terrible can happen that can't be fixed by reflashing the controller. There is no magic in those devices; I make similar things for a living. An upgrade is nearly free; your cell phone was probably upgraded over the air by your cellular provider at least once and you may not even know about it.