California was aiming for a 'feebate' program similar to one in Canada with the primary difference being Canada uses thresholds based on fuel consumption to assign the fee or rebate, while California was considering a sliding scale based on GHG emission.

In Japan, the "Top Runner" program requires all new vehicles over time to approach the efficiency of the best in each of eight weight classes (with some 50%-discounted trading allowed for over-/underperformance between classes); this has improved the overall fleet's fuel economy by about 1% a year even though vehicles have become larger (ECCJ, undated).

In its report, “Winning the Oil Endgame” the Rocky Mountain Institute argues that policy should focus on accelerating market adoption of new technological breakthroughs seen in recent concept cars and trucks that can be made significantly lighter without sacrificing any safety.

“Disruptive technology could make government intervention, though potentially still very helpful, at least less vital: customers would want such vehicles because they're better, not because they're efficient, much as people buy digital media instead of vinyl phonograph records. Automakers could then rely on traditional and robust business models based solely on competitive advantage in manufacturing and value to the customer, and have to worry much less about such random but potentially harsh variables as oil price, climate-change concerns, and elections.”