I was told that it is not recommended to undercoat a NX 300h because the gooey undercoating could cause an issue with some of the electronics or battery things. Is this true? Anyone have an issue having undercoating done?

 

I have heard a similar story, but cannot verify. I have also heard that modern vehicles have better factory rust preventative treatments but can't confirm that either. I understand your weather is more extreme than ours, but I would also be a bit worried about what that extra weight would do to the fuel economy of a 300h. Do you know how many pounds a treatment would add? I'm just guessing that it could add a couple of hundred pounds, or the equivalent of an additional passenger for every single drive. Anyway, I can't answer your question but just adding a couple of additional thoughts.

 

I heard with new cars. If you want to undercoat do it before you drive it around. Otherwise, you may be tapping in dirt and grime that may do more harm.

 

That is not true at all, undercoating acts as an insulator and not a metallic conductor of electricity. I personally don't think undercoating is necessary at all. In ordercars 10, 20 or so years ago sound isulation was horrible and undercoating helped keep out some of the road noise.

 

This is true, if you are going to undercoat do it immediately. But undercoating is not needed.