The properties I look for in this situation for glue is waterproof and flexible. I had good results with Unibond eXtreme but this seems to have disappeared from the market. I'm now looking at Gorilla contact adhesive which ticks the boxes.

1994 +8, BMW Calypso Red.
2002 4/4, 4 seater, BMW Calypso Red.
How do you open the boot?