We must frequent different areas of the city because 95% of the pumps I have used (mostly Esso) are Chip and PIN enabled. Some won't even allow a mag-stripe only card anymore to be used at the pump.

For the US zip code issue, my CIBC Visa does not accept any zip code. My Amex works with the 3 numbers from my post code + 00, so I think it really depends on whatever code your bank returns for the verification, and if the pump decides to accept it or not.

I've also been to some pumps in the US where there are clear signs that a zip code entry is required, I've seen other people being prompted for a zip code, but for my card it bypasses the prompt (likely reads the issuer country on the card)