In addition to what others have said with various feasibility and performance gain issues in the past, what you have described is actually in the works. Likely due to the rise in sustainability concerns, although the company has yet to go into production. I would google aptera motors, so you can see what a real working model of something in this teardrop shape would look.
As you can see its looks kinda dingy, fits maybe two people max, very little space, doesnt look very safe, and its got three wheels. That being said, the draw to this vehicle is that it is completely self charging via solar, and this is possible in part due to its very low drag allowing for very high efficiency.
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