I agree with you that we will probably never see another sub 1-ton compact coupe. The only way it might happen is if we start building Kei-class cars like the Honda Beat or Daihatsu Storia.

But in certain niches of our market, yes. I would expect to see the weight drop by about 5-10% for an average compact sedan. And the steps to acheive that goal aren't radical.

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

When you consider the economies of scale, it makes sense to invest in weight saving alternatives when existing gasoline engines come damn close to meeting the 35mpg standard already.

And I'm glad you brought up the 07 Civic. It shows how efficient modern engine design can be. Despite weighing 2704 lbs, the 2007 Civic EX sedan is rated at 30/38 for a manual. That's within spitting distance of the 92 Civic CX hatch, all while being quieter, roomier and faster.

With a 5 to 10% reduction in weight and a 25% increase in fuel economy, most of the current domestic sedans can achieve the 35mpg standard. The other half of the equation is breaking the cycle of marketing for mastodon-sized trucks and SUVs.

Since Detroit won't reinvest the money on their own, it is time for the government to step in and force their hand.