I think targhediferro is correct again, so only Hint 27 and Rust 18 remain.
Hint 27 says: "The engine maker of these two vehicles had a name derived from a constructed language."
Per Ehhxekt, Rust 18 is a "a Kleinlieferwagen manufactured by the firm Weise & Co. of Berlin, in 1936." I can't locate any information on this vehicle, but the Krejbich used a JLO engine, so I'm betting the Kleinlieferwagen did as well.
I'm not sure how JLO engines relate to a constructed language, but JLO is sometimes spelled ILO, and I think there is an engineered language called ido, so perhaps there is a relationship.