We used it last year for my parents. They wanted one specific, in-demand trim line of one specific model and were not interested in looking at anything else, plus hate haggling, and they needed the car quickly, so it was a good solution for them. As I recall the price was pretty competitive for that model, and they avoided a lot of stress. I'm sure someone with more time and desire to play various dealers against each other, or be flexible about color and features, could have done even better.

Fitz, mentioned up thread, is another very good no-haggle option. They are 100% upfront about their prices, no need to go in and listen to sales BS before they'll start providing numbers. When we bought a Sonata eight years ago their price beat the Costco price, but that probably varies by make. But you can easily get the Costco price, get the Fitz price, and then try to get someone else to beat those targets.

btw, I'm sure there are links and threads out there with positive reviews about Costco's auto program. (I just skimmed through the thread again and realized that it's kind of on the negative side)

You can find reviews about it online, so make sure to research and use your due diligence about the program as well.

But isn't the program mostly online? If it doesn't take too much effort you might as well try it out and see what kind of prices are offered that you can use as a basis for your shopping.

It probably helps to first focus on what you are specifically looking for first.

We checked out prices on TrueCar and then went with Fitzgerald Auto Mall for our Subaru. Super happy with them - they did not try to push any junk fees/add-ons at all and we got a great interest rate.

When I looked into it, I believe that I got the impression that it was powered by TrueCar. Which also powers the car buying service for many other programs. ie through insurance companies, club memberships, credit cars, etc. There was a time when the different programs did things differently and were favorable. But it seems like they are all outsourcing it now and most of them point to TrueCar.
In the past some programs had a fixed price. ie your price will be certain amount of dollars above or below invoice price.

But one thing that's telling is that through the programs now your request gets sent to three different dealers and they all give you a different price.

So actually got quotes through another program but also looked like it was based off of Truecar as well.

The quotes were okay and nothing special.

I still like to use those programs just to get a general idea of prices but make sure to do your due diligence in researching as well.

I don't necessarily enjoy the car shopping process but it's not hard to research things with the internet now. Where you can get a good idea on the price to pay and contact multiple dealers without setting foot in their dealership.

Looking into it now, it looks like Costco might not be powered by TrueCar as I said above.

Here's a recent thread on the BogleHead forum with more details and thoughts about Costco's program:
https://www.bogleheads.org/forum/viewtopic.php?t=177139

We used it to by a subaru in 2013 and really liked it. I will say that some people enjoy the car buying process - I don't so anything to simplify it was, to me, a huge win.

Does anyone have experience with the Costco car buying program - either buying a new car or a certified pre-owned? I'm trying to decide if it's worth my time.

Thanks