Polyurethane injected sandwich panel doors are the best that's available in insulated garage doors today. They're incredibly strong, light weight, and extemely well insulated.
The Thermocraft model, T-12, has a 1 1/8" thick panel with an R value of 10.4 and the T-16, has a 1 3/4" thick panel with an R value of 16.04.
