Autoslash is not "useless" (for me), I (a) still occasionally submit quote requests (although more often not, they aren't the lowest prices, or the low prices are from vendors I would never rent from), and (b) often submit my reservations for AS tracking as increasingly I've found AS comes up with prepay offers thru AS that are fully cancellable up to 2 days before pickup that offer a significant compelling discount. Also, when I do submit a price quote request, I sometimes find if I fully open the responding price quote for other cars, I will find buried in the car list, some decent prices other than the one featured. As for compelling Hertz prices from AS, "forget 'bout it".

Re Costco, I can't remember the last time when I found a quote option that offered great pricing. I rarely even bother to look there anymore. Still like their dogs though!