Yeehaaa! So thanks to EVKen, I've discovered the secret to getting US Leaf CARWINGS to work in Canada is to sign up for a
US CARWINGS account. Setting up a Canadian CARWINGS account actually messes things up. To get a US account, I just had to have a US address, so I used a mailbox address I often use for US shipping.
I also found a way to get around needing a US credit card for getting an American iTunes account:
1. Log out of your Canadian account in iTunes
2. Change country to US
3. Find and install a FREE app, like Nissan LEAF.
4. Sign up for a new Apple ID account. The trick here is that you need to have a US address and a new email account. However, if you use Gmail, you can simply add "+<anything>" to your email account name and iTunes thinks it's a new email, but you will still receive emails to your original account. e.g. if your gmail is
LeafOwner@gmail.com, use
LeafOwner+US@gmail.com. This avoids having to set up an entirely new email account.
5. Choose "None" as the payment. If you don't see this option, you likely didn't try to download a free app yet.
So far, LEAF Link and the US Nissan Leaf app work fine, but I don't receive TEXT message alerts. This is ok since I can still receive email notifications.
Good luck!