Enter AutoSlash*, a new website which opened to the public this month. AutoSlash offers one feature only, car rentals. Their tag line is, "We automatically slash your rental rates!" They do this by offering two unique features:
1. Automatic application of discount codes when you make a reservation
2. Automated reapplication of new discount codes after you make a reservation
I needed a two-day rental in Indianapolis airport, so yesterday I entered the dates and times into AutoSlash. AutoSlash's discount system found me a 12% savings over the lowest prices on Priceline. As a bonus, AutoSlash also seemed a lot faster than Priceline and I didn't have to look at William Shatner. Today I received an email from AutoSlash informing me that they'd found an additional $10 off. Since AutoSlash creates a regular car reservation, you pay at the rental counter and don't need to pay or provide CC information in advance.
$58 - price from regular travel comparison sites (renting cars in Indiana is cheap!)
$51 - initial AutoSlash price
$38 - most recent AutoSlash update
AutoSlash automates what thrifty folks on deal sites such as Flyertalk and Fatwallet have done manually since the era of the discount code. For most people it's not worth the time and effort to troll through these boards for codes and to figure out which codes they're eligible for. AutoSlash does 90% of this work for free for you. The 10% it doesn't cover is membership specific discounts, for example a AAA or Costco member only discount. However, I'd bet that AutoSlash is working on a way to handle these in the future.
On the tech end, AutoSlash appears to be integrated with Sabre/Travelocity, though as far as I know it is a separate company.
I'm going to use AutoSlash for any future car rentals. You should too.
EDIT: There was some problem getting the $38 rental (looks like some of their processing is still a bit manual), so they updated it again, and now it's down to $29(!).
[*] no relation to Cars fanfic