Anyone know if there's a work around for spawning in drivable police cars?

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I've tried all of googles AI ways, still always the same results, don't happen.. even though Google says it's 100% possible to do it.... I've tried through dayz editor with mods also I just no clue what I'm doing wrong, I've got json files that are valid through XML validators json validators but nothings happening, they simply won't spawn or server won't allow it, I'm sure there's thousands seeking an answer aswell for there own community servers, seen YouTube videos of people able to do it,...