I’ve read elsewhere…I think rodbuilding.org…but not sure where or when…but it stated leaving a rod in a car is terrible on it. The heat will soften the epoxies and glues…and uh…can only imagine the results of that happening.
I am a beleaver that leaving rods in the car is a definate no-no and can shorten the life span of nice epoxy finishes. Properly done, epoxy finishes are extremely long lasting, more so on a custom built rod, but UV rays will destroy things faster than we think. I would honestly advise to take good care of your equipment. Proper handling and storage will give you a lifetime of use with your rods.