I dont know about the winter, but this summer, on the Canadian, only the Prestige passengers were able to access the Park Car.
Then someone got it wrong.....hope you didn't miss out on the Park Car!
All Sleeper passengers have access to the Park Car yearround except it is restricted to Prestige only in the summer on the first night only departing Toronto and Vancouver..and also most mornings. From 2pm on all sleeper passengers have access to the Park Car even during the summer.
"Access to the Prestige Park car: Starting April 30, 2017, during peak season access to the Prestige Park Car will be limited to scheduled times for Sleeper Plus passengers. Sleeper Plus passengers will be able to access the Prestige Park car on the following schedule: from 2:00PM until last call 10:30PM, with the exception of evenings upon departure from Toronto and Vancouver where access will be exclusive to Prestige passengers. *Scheduled access times are subject to change.
A select number of seats in the Prestige Park car are reserved for our Prestige passengers at all times in the scenic dome (year-round)"
That was our experience in May, too. After 2pm we could use the Park car because we were in regular sleepers. The first two rows of seats in the dome were off-limits to anyone not travelling Prestige. These were clearly marked.
The Park is classic LD railroading, upgraded. Not to be missed.