Ah, it's for 31 days! rtb, do you realize that you'll earn nothing more for 31 days than for 3 days with promo? Yet you're being charged the fee for every day (because Avis doesn't know that Club Carlson points are on a per-rental, nor per rental day, basis).

I'd say the Club Carlson promo or the Southwest promo are both very poor choices for a 31-day rental (because they're both flat earning, ie, once you satisfy the minimum days requirement, you earn exactly the same no matter how short or long your rental!). But the fee is proportional to do the number of days you're renting!

Do you really need to make it one 31-day rental? You'll earn a lot more by making it (up to) 10 3-day rentals back-to-back-to-back-to-back!

Unfortunately, the way earnings and bonuses are structured, you max out with a one week rental usually, and rarely earn that much more (if any more at all) if the rental is two, three, four weeks.