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Oh, I really like those different strata layers! And the fine grained detail in the rocky, eroded terrain.

We were talking about file sizes a while back - do you have "Tooptimize Tools"? (BlenderMarket)

It seems to work well.
I just bought it because my 'plot-of-land' project was using up almost all of my video ram while I was only about half way through it and I had no idea why. I have loads of geometry, materials and collections but no way to laboriously go through everything to figure out which parts were causing issues. Tooptimize found meshes which were super dense, texture resolutions which were overkill (it can resize them without changing the original) and highlight collections which take up the most resources.
For example, it found one imported object using almost 2GB of texture memory... it was a tiny onion!!! With 8K textures! Absurd. Anyhow, after going through the things it pointed out, I'm using about half of the video memory than previously. The file is still over 1GB though as I had to 'unlink' a lot so that the tool could analyze the materials. (The landscaping flora will probably add another GB

It may not have helped much with your vehicle model as there are probably only a few materials used but could have highlighted the areas using most resources.