You must not have NAV...? All of my sunglasses are polarized and I dont have any issues when looking at the NAV screen.I have only been driving my DC since last Saturday, and it doesn't have Sonar. I test drove a DC with the Sonar option. The rear sensors only came on in reverse, and I believe there is also an On/Off switch. To be honest, now I wish I had the Sonar option because it would help in parking, driving in tight spots, etc. The truck sits up much higher than my Silverado and it's difficult to see what's right in front of the truck. As a side note, I had trouble seeing the backup camera display while wearing polarized sunglasses and decided I didn't need it. Wal-Mart and other stores carry wireless units for a lot less money.