Running lights seems to reduce crashes by about 5-10%, and crashes consume a lot of energy. Depending on crash severity there's at a minimum the wasted time for all involved parties and frequently the necessity for repairs (including the production of replacement parts, paint etc), and at the high end the involvement of emergency personnel and their vehicles, hospital beds, doctors, the production of entire new cars as replacement for totaled ones, etc.

I'm not so sure that running lights isn't a net positive, especially with the introduction of LED lights.