That sounds to me like vital administrative work to do regardless! I also want to distinguish between vehicle size controls and lightweighting. Vehicle size is important for a variety of reasons, only one of which is weight. Likewise, lots of ways to reduce weight w/out messing w/ materials/frame
As a short-term approach, I'd encourage EPA to remove compliance trading from the next round of CAFE regs if they're wedded to attribute based standards (which they seem to be given that they are mandated in the 2005 Energy Policy Act) direct.mit.edu/rest/article...
Abstract. We study attribute-based regulations, under which regulatory compliance of a firm, product, or individual depends on a secondary attribute that is not the intended target of the regulation. ...