Well, it's stuck on everything I've asked of it. (Like brake controllers to dashboards, phone and camera mounts, signs to poles, etc.) But I won't be attaching trunk letters to the car until next spring.
Auto manufacturers have used it for trim and bling for several years, though.
Trailer mfg's use it to stick on siding to utility trailers for a fastener-free look... and that has actual structural constraints, too.
There are high-temp and aircraft variants, too. Here's some application info from the horse's mouth, as it were...
https://www.3m.com/3M/en_US/vhb-tap...MIj9H4l8WI3gIVBVYMCh0AwgjOEAAYASAAEgLsI_D_BwE
Lots more info shows up in a google search, including both company propaganda and "here-hold-my-beer-and-watch-this" videos on YouTube.
I wouldn't hesitate to use it to stick on side trim, letters, badges, or misc. bling. Creating a flat surface on the bottom of the trim would be key, to increase the bondable surface area. I would bet it would even hold on outside rear-view mirrors with the prep below, if you stayed away from car washes. My plan on the trunk letters is to grind off the pins and fill the cavities with epoxy. Let that cure, then apply tape, Xacto to shape with slight undercut, align, pray, and apply after cleaning the surface. While it's difficult to rip off, it does respond to cutting with dental floss thru the foam, then rubbing/rolling up the adhesive with your thumb/fingers. Plastic razor blades can do the job, but more aggressive tools risk the surface finish, as you might guess.
For long skinny trim held on by widely-spaced clips, the task would be to get things flush. But 100% tape coverage might be too much, and would make trim proud of the car's surface by 1/16" or so. So the task would be to get the clips to have a tape-installed height the same as a screwed-on install. I'm not up to speed on what those clips are like, but I'm guessing they would need to be slightly recessed (to tape thickness) before applying tape in that recess. It may be necessary to use more clips to build up total surface area. Designing and 3-D printing clips that are 'just right' might be the best bet, instead of sourcing and modifying original-style clips.
Do you have a close-up photo of the clips?