I had done really long cross country trips with my dog as well (i.e. multi-day cross-country, MI to CA and back), although we had an SUV, where we carved out large portion of the rear compartment for her crate and shoved her comfy bed in there for her. She probably had more legroom than us humans and I think she comfortably slept through a lot of the drive. As the previous poster mentioned, regular potty breaks are helpful. I took my dog out for a quick trot, potty break, and a brief drink of water every time we stopped at a rest area or gas station. I found wet foods (canned if you have to) works better than dry kibble and was much easier for my dog to digest and helped to keep her better hydrated.
Assuming your dog doesn't get car sick easily and that you're not planning on piling the backseat with luggage, I think the dog should be pretty comfortable if she has most of the bench to herself and the 11 hours should fly by pretty quick. Don't forget to bring along your dog's medical records/vaccination record along with you just in case.