This was fun, including an enjoyable final kill at the end of the video.
I've been trying to get Carmageddon 1 running smoothly at high resolutions for years and I've finally managed it due to a combination of factors including a better PC.
3dfx Carma always looks so much better than Carm95, even with the ddraw patch and in 4k with the extended view distance looks better than ever. Really Carmageddon is spoiled by such a limiting draw distance in the standard game.
The trick is not using DosBox and going full VM. This is Windows XP running inside VirtualBox with dgvoodoo 1.5. Including installing windows in the VM it took about 20 minutes to set up.