Hello, for this thread I made a Tesla Base Model 3, it takes 2-3 hours:

-Draw the baselines.

-Make simple normal Networks.
Now my old ISO-lines-Recon-Polyline-Straight-Loft-Sub-D Methode:

Reconstruct Curves with polylines.

Straight-Loft.

get the Isocurves.
The advantage vs a normal Polytool, is you get easy a good meshflow with the Isolines.....:

Reconstruct Curves with polylines./Straight-Loft.
...and you can use the base-network-patches to surface-snaps the Poly-Vertices.

...
The next steps are this way:
Now the first result:
Nice, but the tesla 3 has some sharp lines, they are suddenly stops.
How you can stop the flow and sharp the lines:

Delete a poly-patches where the flow should stop and splite with the subd-split script.

and Repair simply with two lofts, the triangles are welcome in this case.
Now the result, with the first "Stop-Line"

Tadaaaa
the way there too
Result three

more sharping lines
Now the Final Results for the base shape

with baselines overlay
I think for only 3 houres work ist clean enough
now you can use the main power of MoI and Trim Cut the clearance, windows, lights, and all the things you Need.