I've always thought we missed the emissions train (ahem) by not doing the diesel electric hybrid in automobiles. A tiny turbodiesel optimized to drive a generator, with a small battery as a load bank, would likely get somewhere in the 100MPG range even in a larger vehicle.
That's basically what a BMW i3 Rex is all be in petrol rather than diesel and a useful sized battery not a small one. I'm unconvinced a small desiesal is good idea, aren't the emissions even worse?
<fx>tappity tappity duck</fx>
yep, Euro 6 is basically killing off small diesels. (IMHO - yay!)