Modern Cars are Glued Together
It might surprise you to learn that modern cars are mostly held together by glue and tape. I know I was surprised to hear about it. Sure structural pieces and heavy wear items such as door hinges and motor mounts are obviously bolted in place and /or welded. But minor items like side mirrors are often attached using a special double sided tape which was designed for that specific application.
Non-structural body panels are often also glued to the frame using a specially made epoxy which works better then welding or riveting, and also helps reduce road noise. In fact that is the primary reason for choosing glues and tapes over welds, bolts, clips and rivets. Those items cause noise and squeaks. Auto manufactures try to limit these, in order to reduce noise. On items which should never need to be removed of services, they will often epoxy together. Other items use a more jelly like glue, like the door seals, which allows the user to remove and replace them if needed.
The double sided tape (DST) in a car is special tape which was developed specifically for the auto industry. Most cars produced in the last 15 years will have upwards of 30 to 50 pieces of special sound dampening DST installed in various places in the dash board alone, in order to specifically reduce the creaks and squeaks from the components rubbing together as the car shifts.
I heard a story a while back about the 2000 Thunderbird, and how it had so many flaws in pre-production. Many of those design flaws were apparently solved with DST and glue - as regular bolts just wouldn't cut it. That solved the design flaws, and continues to keep major components of the vehicle together.
While it makes for a quieter ride, it also makes for some troublesome times trying to find a decent ground in a vehicle. I imagine most people don't have to worry about that, but as a ham radio operator, it is increasingly difficult to find a solid ground on the body or frame of a newer car when doing an install.
This is one of the main reasons I choose to purchase a Crown Victoria Police Interceptor. They are well bonded and are designed for RF grounding. But doing installs on other vehicles can be tricky. I have found that you are often safer running a separate wire direct to the ground terminal on the battery.
I do not imagine it is anything to worry about however. The glues and tapes used are designed for the hottest summers in the scorching desert, and the coldest winters in Canada. They are designed to resist oils and acids, and adhere strongly to metal. I would also think that they would absorb more energy in a crash where-as a rivet or weld which would just pop off or fracture. Have you ever tried to pull apart a gluey bond? Often it will act like an elastic band and resist separation.
In conclusion, am happy that overall, these advances produce a quieter, easier to assemble car. While it does make grounding and modifying electrical systems in cars more challenging, overall I think that theses new methods provide a better bond then a weld or rivet. So the next time you see a car, imagine how many parts are held together with glue!