Simply put, I always land on my wheels or on the side and slide into a anti-climatic hault. How can I better this?
I wouldn't have expected you to find it, but I think I asked this before. Might want to read through this thread for rolling. https://www.beamng.com/threads/is-rolling-difficult-to-program.59784/
I have managed to roll Sunburst rally car on flat part of gridmap, enough speed and sideways makes good start for spectacular crash.
Setting AI to flee/chase and driving quickly down some dangerous roads can make for some pretty spectacular crashes (and screenshots) (flipped the car over a rock on the side of the road)
I don't take many screenshots while the crash happens, but these are just some crashes I recently took that I like. Sometimes, the aftermath can be cooler than the crash. But like they said above, for rolls, just gotta find the right environment and the right cars. Often times, rollcages make for better and longer rolls (it seems) due to the car staying almost in an oval shape for most of it.