I've recently converted a 1996 Diesel Suburban to run on vegetable oil for all my tours.
The emissions from the vegetable oil burning are carbon neutral--meaning they only emit
enough Carbon Dioxide to feed the next generation of plants that will then be made into oil again.

By buying digital music, you can save the petroleum it takes to press the album
and the gas it takes to truck that CD to you or a store.
All of my albums are available at many digital outlets, including:
Apple iTunes, AudioLunchbox, BuyMusic, DigitalKiosk, Emusic, GreatIndieMusic,
HearMusic, Mouzika, MP3-Extension, MP3tunes, MSN Music, MusicMatch,
MusicNet, Napster, Puretracks, Rhapsody, SNOCAP, Sony Connect,
Verizon V CAST, Weed... and many more.

On my merch table, I now have a tip jar specifically for those who came to the show in a car.
To offset the carbon it took for you to get to the show, I'd suggest throwing in 50 cents-$1 to the
green tip jar. All the money in that jar will go towards efforts that minimize the carbon in our
atmosphere (by planting trees, etc.)