Fuel economy has increased and tailpipe emissions have decreased so much in recent years, we're now squeezing blood out of a turnip - that's Agrarian for Asymptotic. Asymptotic is Math for Declining Marginal Utility - you'll know it when you look back and realize you're past the Point of Diminishing Return. With the great improvement in fuel economy and reduction in tailpipe emissions, we think policy should focus more on incentivizing the next big thing in engines and emissions - but, policy makers are usually fighting the last war instead of looking ahead; so, we don't hold out much hope. What to do? Embrace remanufacturing, use an existing engine (parts and even the whole vehicle) that are 'good enough' and use less resources than making a new one. Make no mistake, we are advocates of research and development; we love technology advancement. Policy makers, when you realize you're on the flat part of the curve above, take it as an indication for the need to innovate and start over at the bottom-left.