"If a bolt has got only, say, to 1/3 of it's plastic deformation zone, when it's fully released then tightened back, it still starts with elastic deformation, only the plastic deformation zone will arrive at a smaller torque this time. I suspect most car bolts don't go past 1/3 of the plastic d...

Thanks for sharing this information, cyrpobooja. I never would've figured that out in a million years.