Don't forget to take into account that fuel economy standards get more and more lax as GVW increases in a step-wise fashion (at least in the US). If you look at

Don't forget to take into account that fuel economy standards get more and more lax as GVW increases in a step-wise fashion (at least in the US). If you look at historical data, cars and trucks have been increasing in size and GVW at a rapid pace. Car companies are quite literally incentivized to make larger vehicles (and pass that materials cost onto us) while lowering R&D costs for their powertrains, and as a result, killing the environment even faster.