Actually the primary reason to switch was because effective Apr 19th Citi Premier changed the earning schedule to 3x TYP on travel while the AMEX Plat earns only 1x.

When the reservation was made, the AMEX Plat was stored in Avis Preferred, so it was the default billing card. I later changed the stored card but then found out it would only be effective with NEW reservations, would not replace the previous stored card that attached to the old reservation! I could not change the reservation due to the rate had gone up 15%.

Both the AMEX Plat and later the Citi Premier were authorized, for the IDENTICAL USD at $285xx. AMEX Plat was authorized at Pick Up. Citi Premier was authorized at return when I asked to change card. Why it was not exactly $100 over the contract price of $175xx, but $110xx is beyond me. (Avis always added some extra to the rental cost for authorization though I never figure out how they calculate it - it also seems each country has a different calculation.)

Obviously Citi card was not DCCed because the authorization in USD was identical to that made on the AMEX Plat, and the 2 were done 5 days apart.

Actual billing was to the Citi's card while the authorization on the AMEX Plat fell off after 2 weeks.

I am just real puzzled on how Avis handles its billing these days - it seems being determined by the exchange rate at reservation and then the home currency became the contract price, and the local currency varies based on the exchange rate against the FIXED home currency amount. This is the first time I have seen such. Earlier this year in South Africa and in Turkey, it was not like that - both were just straight local currency at billing, regardless what the USD shown on the reservations.