The added purchase price is a turn-off. If they didn't do that, we'd all be driving little turboD's and not sucking up enough tax money in oil sales. They'd have to raise taxes on fuel to offset the differentiation.
Diesels are great for daily drivers, and recent advancements have made diesels cleaner- as well as extending oil changes. Diesels dirty oil, not overheat it or burn it like gasoline engines do. With good filters you can go quite a ways (25k miles) without an oil change- which is good because diesels tend to have larger oil capacities than gasoline engines.
Go green? Yeah with funding for algae and other alternatives to petroleum, some day we could possibly supply all our own fuel here, and stop financing terrorists. We could probably lead the world in fuel cell technology if the government could figure out how to tax water like gasoline.
Where's this car Ford?