I think of PHEVs as a way to unlink from a rigid fuel distribution system by utilizing electro-mechanical power generation. Relying on electricity to move the car, allows for a neutral energy choice platform. This is absolutely much better than a non-neutral energy choice platform like a strictly mechanical engine that might run on pure gasoline, pure diesel, pure ethanol, pure natural gas, or even pure hydrogen.

If I want to slap some solar panels on my house, then I can have no fuel impact whatsoever. If I want to plug in to the grid, and pay the renewable energy rate like for wind, I can have no fuel impact. If my car is a PHEV designed to generate electricity from gasoline, it's designed with modularity in mind, and we run out of gasoline, I can simply pay to have the electrical generator replaced with another fuel source like ethanol or hydrogen without buying a brand new car, thus eliminating a lot of waste.

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What about the development of a solar panel roof on Plugin cars. They could be manufactured to recharge themselves constantly. This would eliminate the need for the Plugin factor completely if enough effort were put forth into the development of this type of technology.

No, you will still have to recharge. Solar power, at 100% efficiency, will produce 1.4kw/m^2 in perfect conditions. At 60mph, the Chevy Volt will consume 12kw (40 miles=8kwh). Unless you have a very large car, you will not be able to keep the batteries charged and will still need to plug in or have an onboard generator.