Batteries are not good for the environment ... Lead ? lithium ion? Ouch any way you want to slice it
If you want to really be 'green' keep driving whatever car you have today for another 10 years. The energy required to produce a new car is waaaaaaaaay more than any delta in energy savings you will give back to mother earth by getting something more efficent. Better yet keep the car 20 years. When it stops working figure out some other way to get to where you need to go. If you want to be green the last thing you want to do is consume more. Buying a new car to replace a working one is in no way green.
"The problem with natural gas-powered cars is that the fuel has to be stored in a liquid state under pressure. Imagine the carnage." .....have you seen large banks of lithium ion batteries catch fire? Now that is impressive. Batteries are stored energy just like natural gas. When things go wrong, that release of energy is impressive