* Use CFRP to replace the steel side impact beams.
* Increase use of aluminum or FRP for roofs, trunks and hoods.

you can't simply substitute materials and not retest and reengineer. all these take time and a lot of money. I have a friend who is a material structural engineer. he had to redesign a whole cabinet chassis using aluminum instead of steel because chinas consumption of steel made it too expensive to use. he spent nearly 3 months redesigning and testing the cabinet to be built using aluminum. every says make it lighter and lighter but they don't consider the magnatude of engineering that is involved whenever a material is changed. trunks and hoods on cars these days are part of the crumple area which protects the occupants, you can't simply change those parts with aluminum or other materials. also for manufacturing, aluminum still costs more than steel. lighter = more $$$

yes the civic is fuel efficient but it's not a car every wants to buy. which is my point.

10% reduction in weight is not an easy feat. would people still buy the same car if they had to pay about 10% more which was 10% lighter? probably some would but who wants to after a market where only some people will buy the car?

25% increase in fuel economy? you can't be serious? everyone would be driving underpowered nofrills nothrill cars and paying extra for the previlage.

what would happen to small independant makers such as BMW/Porsche/Ferrari, etc? even if they are able to meet 35mpg, the rest of the requirements which calls for 4% every year up to 2030 is idiotic.