我最近查过CIC的网站,上面的解释如下:
15. Can I use my IMM 1000 to travel to the US in my own car?
Yes.
As of December 31, 2003, the PR card will be required to re-enter Canada by commercial carrier (airplane, boat, train or bus). This requirement does not apply if you are travelling by private vehicle. You should contact the US immigration services about their document requirements.
13. What happens once the December 31, 2003 deadline has passed?
Permanent residents will still be able to apply for the PR Card in Canada after December 31, 2003.
The December 31 deadline only applies to permanent residents who will be returning to Canada on or after December 31, 2003 by commercial carrier (airplane, train, bus or boat).
To avoid possible travel delays and additional costs, we recommend that permanent residents obtain a PR Card before travelling overseas.
Permanent residents, who do not have a PR Card and who are overseas on or after December 31, 2003, and who will be returning to Canada by commercial carrier (airplane, train, boat or bus) will need to obtain a Travel Document. Note that a Travel Document is available for one-time use only, at a cost of $50.
You should apply for a Travel Document no earlier than six months before the date you expect to return to Canada.
Permanent residents may apply for a Travel Document while they are overseas only. You cannot apply for a Travel Document from within Canada.
A Travel Document is not intended to replace the PR Card.
http://www.cic.gc.ca/english/pr-card/prc-issues.html#deadline