If you start a race and then teleport to a deathmatch zone you will be invulnerable, immortal. I tried it several times and it always worked. I recorded it, so its easier to understand.
Found: 2021.12.04.
UPDATE(2021.12.05.):
God mode has to be turned on, so the problem is if you are in a race and you teleport to a dm zone god mode remains on (i think).