https://1drv.ms/u/s!AoPEwcmh86n10C6N1...
You get in this file:
Blender file set up ready to render Height Map
Rendered Heightmap used in this video
An image that shows the Shader map for rendering Height maps

Be SURE to save your renders as "theTerrain_heightmap.png"
Be SURE to save Black and White 16 bit
And be SURE to render at 16 Bit in the render output options black and white
Only render resolutions power of 2 square. Examples:
512x512
1024x1024
2048x2048
4096x4096
8192x8192 (This is also max allowable size for BeamNG terrain importer)
If one wants a map larger than that, they would have to change the default block size in the options to 2, 4, or 8 for example. In contrast to that a block size can be less than 1 also. Point .5 or point .1 for example will densely pack a maps terrain block squares even smaller. This is great for artists who love fine detail for terrain painting or sculpting in the world editor terrain tools.
Making an 8192x8192 with a block size of 0.25 will in reality be a 2048 x 2048 map with 1/4 the size paint brushes. Before you get too excited, it still will have the massive poly count of the 8192x8192 map.

Also very important, after your map is generated after import, do not delete the warning material in the terrain painter until you have at least a 2nd material for it to fall back too. Or it will crash!