You do have to heat them up and stretch them. Adding spray adhesive with an "activator" to increase adhesion is also required.

Unfortunately, that alone will not last for long. You need a way of permanently attaching them back to the doorcard itself. I normally use a staple gun on the return edge where it can't be seen @ the top.

Remember, these vinyl covers were originally blow-moulded 1st, then stuck onto the card, not laid on and stretched to shape. Hence the problem.

I have spoken to a few trimmers as well, and no-one is prepared to recover them using leather or similar, due to the number of curves and lines involved.