From ASC's website:
1991: "ASC builds 100,000th GM Cavalier and Sunbird Convertible"

1989
ASC introduces first production convertible pickup truck, the Dodge Dakota Convertible

2000
ASC opens Munich, Germany technical center for European open-air development

By the way, they define low volume as capping around 40,000 vehicles per year (per model). I doubt there is a convertible maker out there who isn't capped around there somewhere.

Nate