Earth friendly logo/name design for hybrid vehicle mfgr

We need a logo designed for our company. The logo must be presented in vector format for use in Photoshop/Illustrator. The logo might be used on vehicles so it must look good in single color or as an emblem. Our company name, "Proterra", can be part of the logo or separate.

http://www.ProterraLLC.com

We are a manufacturer of buses and trucks that are light weight all-composite body, battery-dominent to dramatically reduce our dependence on oil as the dominant fuel for vehicles. The vehicles are cutting edge designs and very green by emitting low/no emissions. We want the logo to reflect these attributes. We have thought about using an earth as a basis for the design, but we are not by any means limited to that. We are interested in seeing creative ideas. Vehicles do not need to be involved in the design since we believe that our business will evolve to include many Earth-friendly products.

- We like the name to use Eurostyle Extended Two font, but we are open to other suggestions
- We like a darker or deep green color for the name
- We plan on using bright or deep blue with a tan or southwest style background
- We are open to any new ideas
- Something crisp, something sharp
- Please be creative

- We are not interested in a picture of a vehicle in the logo.
- We might consider it if it is very creative and doesn't single out a particular type of vehicle, but would rather not see one at all