I had some cracking along the top edge of mine and in order to stop the crack from getting worse, I used JB Weld. It worked like a charm.

I am sure it would hold vinyl to metal as well. The repair was done 5-6 years ago and is still good as new.

carpenters contact cement

There is a product called barge cement that white water runners use to glue knee pads to the bottoms of canoes. It's kind of a super duty contact cement, and water proof too. Comes in a small metal 1/2 pint can. You can buy it at stores that sell white water boats and rafts. It's not cheap.

The only problem with it (besides the cost) is you only get one shot at getting it right, because the way you glue it - is the way it stays.

Barger cement can be had at shoe repair shops too.

3M makes a vinyl trim adhesive that's used to glue plastic trim back onto your auto. I've had great success with it and you can buy it at NAPA.

Amen on the barge cement. It does come in tubes too.