Rather than purely hidden, it could plainly have a message about something being wrong (“you hear a strange noise from the engine, might want to look into that”, “Your isn’t riding as well as used to”), but require examining the vehicle (no player time spent, but a long action of a few minutes to give the vehicle a once-over) to get a diagnosis and way to repair it, such as a patch for a tire or radiator, or a replacement engine component, or in extreme cases replacement of the entire part to make the problem stop.
What I’m thinking of is attaching a list of things that can go wrong to specific vehicle parts, along with what causes them, messages to print about them, and something resembling crafting recipes to repair them.