Hemp sequesters CO2 and makes a very tough composite body. (I have no idea of cost comparison but the industry is new, passionate & hungry for business.) https://youtu.be/Hx8OTH0eEM0
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The BMW i3 uses hemp, albeit not for the body which is carbon fiber and recycled plastic.
From line 95 of Aptera's FAQ Spreadsheet: "Aptera is made of carbon, kevlar, and hemp"