What would be a good logo that advertise the system of clean diesel?

Question

I'm trying to think of a logo that would work that might be seen on the back of buses or cars showing that they use diesel as a fuel source. An example of this kind of logo could be how a lightning bolt advertises the system of hybrid-electric.

Answer 1

They already have one. It is like a round broken up gear around a drop of oil.

http://www.chevrolet.com/fuelsolutions/

The symbols are on the top right