Genuine question here: I keep finding conflicting information about how much environmental impact a car's manufacturing has, relative to its lifetime use. I too

Genuine question here: I keep finding conflicting information about how much environmental impact a car's manufacturing has, relative to its lifetime use. I took a very good math-based sustainable design class as an undergraduate, and we were constantly shown numbers that indicated a car was a "20/80" product (20% or less of its impact comes from manufacturing, as opposed to "80/20" products). But I'm certainly willing to believe the information I learned in that class was mistaken or outdated. The research paper linked to from one of the linked articles (I followed the rabbit hole down a ways... http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00532.x/full http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.... it's the Norwegian study mentioned in http://spectrum.ieee.org/energy/renewables/unclean-at-any-speed http://spectrum.ieee.org/energy/renewables/unclean-at-any-sp...) says " vehicle production is not insignificant, contributing on the order of 10% to the life cycle GWP." However, the article, and the statement from Maureen Cropper (who presumably knows what she's talking about) says that the majority of the impact comes from the manufacture of the vehicle. Am I confused? Are people talking about two separate measures of impact, or is there something I'm missing? Having trouble reconciling all of this info.