I asked @meywue a while back, this is how he responded: "Einfluss Technik Kraft", which roughly translates to "Impact, Technology, Power"
ETK is also a term used by (at least) BMW people in Germany referring to the catalog of replacement parts. ("Ersatzteilkatalog" ) That's more of a happy coincidence than anything else though I think.
I'm sorry for being rude this thread, but this has been discussed before. https://www.beamng.com/threads/what-etk-means.22463/ please use the search button or google search