Baseline (Widescreen) Solution & Issues
Native, Hor+, HUD stretch.
Ultra/Super-Wide (21:9/32:9) Specific Solution & Issues
Eyefinity / Surround Specific Solution & Issues
Native, Hor+, HUD stretch.
As can be seen on previous screenshots, the optional wing mirrors (displayed only when the "real" mirrors are offscreen) are Vert- in widescreen because their frames stretch. This does not really hurt the gameplay since you see as much of the road behind you (just less sky). All two-dimensional UI elements stretch. The PDA's map is Hor+, although all symbols on it strech. The truck showroom is Hor+.
4k UHD Specific Solution & Issues