The likely issue with the car thing in the original post is that you’d potentially struggle to get it registered for uk road use.
It would need to pass an SVA test (single vehicle approval) as no part of it would be type certified, and as a result something as stupid as a light lens being the wrong colour (not red or orange enough) or lights being in the wrong place etc, you would then likely never get it past the test.
The Tesla Cyber truck as an example will not past the rules in most of Europe because of the sharp edges and aggressive shape which would present a risk to pedestrians. There has been one in the Uk to my knowledge brought here by Tesla to show off but I don’t think it was road legal as they trailered it around between show locations
