GMC Envoy? My Envoy came with cloth seats that are not very comfortable. Who would I contact for an upgrade of the seats would the dealer do this? What price range are we looking at? Can you switch to Heated Leather. If you can do seats could you add a navigation system to an existing car or the steering wheel with the buttons for the radio? After looking over new cars I'd love to stick with my Envoy because it's only got 22000 on it but I'd like some luxury added as well.