I think that Toyota would be really clever to sell a diesel Prius along side a petrol one. That way, the general American public could see that diesels are better for FE without the old downsides, and it would make for one hell of a FE car.
On the other hand, huge amounts of resources go into building a hybrid, so I actually think that environmentally it would be better to just offer non-hybrid diesels at prices that are close to the petrol equivalent (even if that means jacking up the price of the gasser).
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