Poor Maintenance

Source: Codex: Genestealer Cult, p. 5

Cults usually have little time or expertise to maintain any vehicles they may steal or capture. This generally results in erratic performance on the battlefield. To represent this, after moving a Cult vehicle in the Movement Phase, roll 2D6. On a roll of a '2', the vehicle has breathed its last, and is Immobilised for the rest of the game. Otherwise, it can continue to operate as normal. This rules [sic?] does not apply to the Cult Limousines – as you can imagine, the Cult Leaders make sure these vehicles are very well maintained!