The Town Car V8 is FFV, though I believe that means it is capable of using ethanol, not propane or CNG.
It does suck that you don't have the base Signature model in Canada. It would pare away a few features ans reduce the price tag.
The rear seat of the Chrysler 300 is not impressive. Room is just OK for such a large car, and the high windows make you feel closed in. Because the windowsill is so high, I found no good location to rest my arm.
I do wonder if the Town Car is really going away, or if it will continue as a fleet model (much as the Taurus has). Lincoln has the vast majority of the livery market and they would be crazy to throw that away.