With the success over the last few years of hybrid cars like the Toyota Prius, recently hitting one million sales worldwide, the possibilities for fuel-saving cars continue to expand.

Electric cars, semi-electric hybrids, cars fueled by hydrogen, plug-in hybrids (PHEVs), compressed air as fuel, diesel hybrids and more are entering the market and you can now even make simple modifications to improve the performance of your not-so-green vehicle.

If you own a diesel car there are now cheaper and cleaner options with many biodiesel fuels available. If you are really inspired, you can even make your own biodiesel at home!

But finding the smartest technologies as well as building safe and affordable cars isn't an easy science to perfect. Many of these cars are not yet past prototype stage, and can only be seen at various car shows around the globe.

Certainly the future points towards improved electric cars, more smaller and lighter cars like the Smart Car, and at this point in time an expanding range of hybrid cars entering a growing market. So if you're even considering buying a 'greener car', it's time to get stuck into some homework before you part with your hard earned dollars.

There are all the considerations of a normal car purchase as well as some newbies-

• How do hybrid cars work?
• Do hybrids have problems that standard cars do not?
• What about their life-cycle, how intensive are they to produce, and how expensive are hybrid batteries to replace?
• Price, yes they are more expensive, but how much, and how long will it take for you to recoup these savings?
• What sizes do they come in? Got a family of 5? You might just need to look elsewhere for your new wheels!
• What are the benefits of driving a hybrid?
• How much will you be reducing your fuel bill by, after all we are attempting to reduce our impact on the planet here, aren't we!