16 months ago, but the rules haven't changed. If you're driving in a private vehicle (including a rental car), you will be allowed in with your passport and CoPR.
This stems from the fact that PRs have a right to enter Canada. If you can manage to make it to a Canadian Port of Entry, and show the CBSA officer proof that you are a PR, the officer has to let you in.
PRTD and PR cards are required to travel on commercial carriers. Planes, trains, etc. Driving to the border (or walking to it), doesn't require a PR Card or PRTD.