These sketches just prove that BMW's designers are going on drug-fueled rampages with paper and pencil.
At one point is looks just like a Mazda 3 hatchback 😭
I'm a little bit familiar with the back-and-forth process on design vs engineering due to a friend working in Chrysler's wind tunnel up north. It gets pretty serious when the designers are at the point of creating scale clay models. They'll make a physical model, send it to the aero guys who scan it into CAD, run CFD, make changes, send those changes back to the designers, etc. This will happen several times and can get very annoying when you're ironing out the final details for that little bit of design flair vs little bit of efficiency.
Note that the designers were at least smart enough to want a proper hatchback on a CUV. At no point in this designer's sketch history did a fastback show up (I struggle to call it a kammback because the rear slopes all the way to the beltline). But this is a more efficient greenhouse design for the EV version, and I have to assume that BMW's aero engineers had to tell the designers that a hatchback could never meet their efficiency targets, and the designers were forced to change tactics, and the bean counters decided they couldn't afford to offer both a fastback and hatchback, so they decided to stick with a completely useless fastback CUV which is precisely what buyers of tiny CUVs
don't want.
Look at how spacious this hatch is:
Dang that looks like a fun, practical little CUV, innit? I bet you can stick like four carryons stood vertically in the back of that, plus another on top.
Edit: I think I realized what happened. BMW is doing the whole odd/even traditional/coupe numbering scheme. The 2023 X1 is basically the same size as the 2024 X2, except the X2 is a coupe.