Smart Fuel Cars

When do you think the auto companies will begin to push out more economical or gas alternative vehicals. I watched a report the other day that said they are ready to produce but the government isn't pushing for it so they aren't pushing it. It showed vehicles that would plug in when you got home at night and if you ran the battery, it would switch over to regular fuel. With the high cost of fuel you would think we would see more of these vehicals but think of the gas tax that the government collects on our gas, maybe that is why they aren't pushing it so much? What's your opinion