This all depends on several factors.
Your financial situation
Your reasons for wanting a hybrid
Your transportation needs
First on a cost basis, it is doubtful the current generation of hybrids will actually save you money. This all depends on what your transportation needs is and how you drive your car.
Next from an environmental standpoint, there are many options that you should first consider such as joining a car pool, biking/walking more, moving to live closer to work and other amenities, living in cities that do not need cars.
I would personally recommend moving closer to work and getting a bike, but this is not always possible to many people.
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