On the TBD "Hybrid Vehicles" page I opine that it would be better if the current crop used the "serial hybrid" design. The point I tried to make is

It's not electric unless you can plug it in.

The current hybrid vehicle designs all continue requiring that you burn gasoline. That the vehicles are still burning gasoline means that the overall dependancy on oil continues. There are many reasons to end the dependency on oil, and that's why I am a purist about electric vehicles.

A plug-in hybrid vehicle, like the Chevy Volt, Fisker Karma, or Ford C-MAX Energi, use a larger battery pack than regular hybrid vehicles, and the car can be plugged in to recharge that battery pack. This gives the car an electric-only range longer than the regular hybrid vehicles, and in some cases the plug-in hybrid owners (cough cough Chevy Volt) get to thinking they have an electric car.

The plug-in hybrid is a nice pragmatic choice between gasoline, hybrid and all electric. It has the electric-only choice along with the illusion of infinite range you get from gasoline powered vehicles.

History

The first plug-in hybrid was Dr. Ferdinand Porsche's first car back in 1910. It had four hub motors, one in each wheel, and set land speed records of the time (65 miles/hr).

The modern plug-in hybrid came into being when groups of individuals worked together to develop an open source conversion kit for the Prius. The CALCARS advocacy organization grew out of this project.

It turns out that the Prius has an "electric-only" mode which is enabled in Europe and Asia, but not the U.S.A. Hmmm, one wonders why. This is a different sort of hybrid vehicle, namely:Plug-in Hybrid Electric Vehicle (PHEV) Web site: http://priusplus.org/

How the '04 Prius Can Become a PRIUS+ Plug-In Hybrid - We can take this well-designed, highly popular advanced vehicle and soup it up -- or more accurately, "green-tune" it! Add batteries and grid-charging, and you get PRIUS+, a "neighborhood-speed" plug-in hybrid (PHEV). That means no gas when you do your errands on local streets at 35mph. On the highway, it runs just like any other Prius, with the gasoline engine doing most of the work.

They noted that there is empty space underneath the hatchback area. That empty space can be used to install an extra battery pack. In the Prius, the control computer (HV ECU) already knows how to run in "electric-only" mode, and this is enabled through a simple pushbutton on the dashboard. This button is missing in U.S. Prius's.

On the Prius Plus web site are instructions for installing a button for this use. It's simply a matter of running wiring from a button installed into an already existing panel, to connectors on the HV ECU. The instructions do not discuss installation of extra batteries.

Presumably the extra batteries would simply be wired in parallel with the existing battery pack. You could then run a charger connected to both battery packs, and be able to charge them independantly of running the gasoline engine.

Some advantages are:

• Increasing gas-mileage even further, and decreasing emissions even further (NOTE: It can actually decrease mileage and increase emissions)
• Lifetime service costs could be lower, as it reduces the use of the gas motor (electric motors are far more reliable)
• For short trips around the neighborhood, your entire trip could be electric