research greenest -- Airlines, Gas Stations, Rentals

Could someone research the greenest airlines, gas stations, car rental companies? (This is maybe 3 1-hour projects, great for a new volunteer.) We may try to get discount codes for the greenest airline[s] and share them with client events [Does Jetblue count as green for discouraging airline travel through abuse of customers?] The other info we're likely to just clean up and post.

Bonus: Find the sponsorship information/contact at the greenest companies.

Note: the airlines seem to call this "Meeting" travel, NOT "Group" travel (Group Travel would be a bunch of friends going on vacation *together*.)

Dear Airtran, [sample -- we already have this agreement with Airtran]

SpaceShare helps people travel together to large events, sharing their ride or flight. We're planning to work with hundreds of large events in the coming year and years.

We would like to be able to offer the event organizers a discount code: having many event attendees on one airline makes it easier for us to connect them. If you are interested in offering group rates to large conferences and festivals, please let us know:
1) If there is an easy, automatic way we can pass a code on to interested event planners. What are the rules, details? Is it possible to keep this simple and automated for the overworked event planners we're helping?
2) If SpaceShare would receive benefits for sending passengers to your airline.
3) Please let us know your airline's environmental status and policies. Our organization is committed to promoting green options whenever possible.

Regards,
Stephen