http://www.alternativefuelstips.com
There are some environmental group programs such as 'Alternative Fuels Conversion Program' that will help you in terms of money if you do want to replace your car with a more energy efficient car. This program provides gives for up to half the cost to managers and fleet owners for them to purchase LPG or Natural Gas vehicles or to get their cars converted into LPG or Natural Gas vehicles.
http://www.alternativefuelstips.com