Some of those kit cars are cute, but I don't think they'll ever make it in mainstream America. I think the average American might consider a diesel hybrid if it saves him/her money on fuel and maintenance costs, but they're going to have to be big, loud, and carry a lot of cargo to compete with SUV's and other vehicles that are popular in America.
There is already a niche for small fuel efficient vehicles, but if you're willing to give up weight and power, you might as well go all electric.
Just my $.02
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