I first learned about the prohibition against Canadian licenced drivers taking US plated vehicles over the border from reading the Zipcar website:
http://www.zipcar.com/how/faqs/faq?subject=drive_away_us
If I reserve a Zipcar in the US, can I drive out of state or in Canada?
Yup. Knock yourself out. Don't really knock yourself out. At least not while you're driving anyway.
If you'd like to drive to Canada, contact us at least 3 days in advance. We'll need to issue you a special insurance card to take with you, so make sure to plan ahead. (Exception: if you are a Canadian resident or a Canadian citizen residing in the US and have a Canadian driver's license, Canadian Customs prohibits you from driving a vehicle with US license plates from the US into Canada. Sorry, that includes Zipcars.)
However, in searching around for an actual reference on the CBSA website, I found this interesting link:
http://www.ezbordercrossing.com/the-inspection-experience/rental-cars/
Canadians Driving a U.S. Rental into Canada
Before June 1, 2012, it was very difficult for Canadians to bring a U.S. rental into Canada. As of 6/1/12 Canadians can drive a U.S. rental car across the border into Canada without paying GST, HST, or Green Levy taxes if they meet all of the following requirements:
You have been out of Canada for more than 48 hours
The vehicle is for non-commercial use
You return the vehicle to the U.S. in no more than 30 days
This is useful if a Canadian tourist fly’s into the U.S. and then decides to drive back home to Canada.
So according to this, the rules
just changed. Sadly, they don't cite to any authoritative source.
Here's a quotation from the Budget Rental Cars website:
If you’re a Canadian resident, Canadian Customs regulations prohibit you from entering Canada with a U.S. car. So renters with a Canadian driver’s license and a U.S. license plate won’t be allowed to cross the border into Canada.
Source: http://www.budget.com/budgetWeb/html/en/customer/commonquestions/index.html
Aha! And it took some digging but here is an authoritative source, dated June 20, 2012.
http://www.cbsa-asfc.gc.ca/publications/dm-md/d2/d2-4-1-eng.pdf
Terms and Conditions of Importation of Conveyances
3. A conveyance may be imported if,
(a) the conveyance, while in Canada is to be used
solely for the transportation of a resident and
accompanying persons from the point of arrival in
Canada directly to a specified destination in Canada
Memorandum D2-4-1 June 20, 2012
2
and from the specified destination to a destination outside Canada;
(b) in the case of a commuter, the conveyance while in Canada is to be used for the personal transportation of the commuter and accompanying persons from the point of arrival in Canada to specified destinations in Canada and from a specified destination in Canada to a destination in the United States;
(c) in the case of a resident other than a commuter, the conveyance is to be imported only for the purpose of transporting his household or personal effects into or out of Canada, or for personal transportation as a result of an emergency or unforeseen contingency;
(d) in the case of a commuter, the conveyance is to be imported for the purpose of personal transportation of the commuter and accompanying persons between his place of residence in Canada and a point in the United States or for the purpose of visiting clients in Canada on behalf of his employer;
(e) the conveyance is not to be used in Canada for the purpose of
(i) touring or other leisure activity,
(ii) carrying passengers or goods for hire or reward,
(iii) transporting goods for sale, or
(iv) soliciting sales or subscriptions on behalf of an employer who operates a business in Canada;
(f) at the time of importation, the person importing the conveyance specifies to the customs officer the date on which that person intends to export the conveyance from Canada; and
(g) the conveyance is exported from Canada within the time limit specified in section 5.
4. Revoked (SOR/88-84) January 20, 1988.
So there you go -
you can now bring a non-Canadian registered car into Canada, with a Canadian licence. But only since June 20, 2012.
Note that it also provides a citation to the previous law (SOR/88-84).
So all those previous sources are now incorrect.