By far the best way to reduce fuel cost and other associated automobile costs are to, well, eliminate them. In today's world this isn't as far fetched as it may seem with videoconferencing.
Many people are familiar with and use consumer level videoconferencing like Skype and Microsoft Live Messenger. These products work adequately for home use. They have the ability to conference call multiple parties. They are also free. They are especially useful for one to one video conferencing with low to mid range quality.
The next level of quality is the high end professional level conferencing. One product is DimDim. This is an open source videoconferencing product. You can pay a small fee to use DimDim's servers or download the source code, install it in your office and use it totally free. DimDim is a high quality videoconferencing solution that can be used for pure conferencing, computer training, etc.
Another pay as you go solution is Cisco's Webex. This service is especially useful for computer training.
With some use of technology, fuel cost can be dramatically reduced.