In our last issue, we told you about Northwest’s “Mileage Accelerator” promotion, through which WorldPerks members earning miles from Alamo, Dollar, National or Thrifty will have their miles — all miles, base and bonus — matched by Northwest.

We had pointed out that Thrifty offers 250 miles for rentals up to seven days, and 500 miles for rentals of eight days or longer, and thus offered a potential advantage over other partners offering just 50 miles per day. We’re pleased to correct ourselves and point out that Dollar, too, offers the same earning level as Thrifty, and is thus a consideration for those of you looking for the best deal.

And, since we last spoke, all four car rental partners have sweetened the deal.

Alamo is offering one free upgrade and double miles until Nov. 15; Dollar is offering triple miles until Dec. 15; National is offering double miles and 20 percent off through Dec. 15; and Thrifty is offering triple miles until Nov. 19.

Register at http://www.nwa.com prior to renting and use promotion code 8652.