Some say that only when Batteries are developed both lightweight and economic to the environment, the overall cost is just no worth the effort.

So the cost outweighs the savings.The weight and life expectancy of the batteries make the vehicle inefficient. The existing technology makes for an ever increasing environmental catastrophe, both in manufacture and disposal. The only two realistic options for eclectic vehicles is to tap into the energy already around us, ie sun and electromagnetic means. That’s not developed fully yet. And then there’s self-contained energy units, Not batteries, but units that Create energy from a electrochemical reaction, thus creating energy from environmentally sustainable sources like water Co2. and methane substitutes. Problem being, whilst there is a wealth of alternative energy suppliers, no1 will develop them soon for serious financial reasons.

I wouldn’t say that there are a ton of pros for hybrid cars now (you get into the yuppie ‘i’m an SUV-driving environmentalist’ clique!).

They are more expensive than their non-hybird counterparts to the point that even if you drive them 100k miles, it won’t be enough to end up ahead (unless gas goes up to $5/gallon).
On the Honda Civic Hybrid, you can’t fold down the backseat into the trunk.
There are more components (including batteries which will probably need to be replaced during the life of the car — and those are more harmful to the environment than the extra gas you’d burn).
The added weight to the vehicle doesn’t help efficiency or road wear either (lighter weight vehicle would be better).
In addition, a hybrid severely limits your auto choices (and they start at about $20,000 v. the $12,000 that all cars start at).

Maybe hybrids will be worthwhile someday…just not today.