Ecto-1, the Ghostbusters' signature car, receives some retcons in Ghostbusters: Afterlife. As beloved as the classic Ghostbusters team of Egon Spengler (Harold Ramis), Ray Stantz (Dan Aykroyd), Peter Venkman (Bill Murray), and Winston Zeddemore (Ernie Hudson) tends to be by most, almost equally iconic are some of the props and equipment associated with the franchise. Many of those items reappeared in Ghostbusters: Afterlife, such as the PKE meter, the ghost traps, the proton packs, the red phone used to answer calls, the firehouse, and of course, Ecto-1.
While Ecto-1 isn't exactly a showpiece when acquired by Ray in the first Ghostbusters movie, it looks pretty nice when spruced up a bit, and it's impossible to imagine the Ghostbusters brand without that vehicle. Amusingly, the Ecto-1 car was actually originally a hearse, which makes sense, considering the Ghostbusters are also using it to transport dead people. The difference is that now it's the souls of the deceased instead of their bodies.
As the Ghostbusters movie franchise has gone on, the Ecto-1 has become even more vital, as versions of it have been merchandised in basically every possible way. It was an even greater focal point in the classic Real Ghostbusters cartoon. There was never a question that Ecto-1 would return for Ghostbusters: Afterlife, as the earliest marketing for Jason Reitman's sequel featured the car. However, Ghostbusters: Afterlife surprised many by retconning Ecto-1's appearance, undoing changes made to it in Ghostbusters 2, and also seemingly its ownership history.
In Ghostbusters 2, Ecto-1 is given some upgrades and changes, being rechristened Ecto-1a. This includes more gadgets being placed on the top, a new logo celebrating the Ghostbusters' reformation, a slightly modified paint job, and digital announcement boards on the sides. 2009's Ghostbusters: The Video Game — which was said to be canon by Dan Aykroyd, and partially adapted the original 1990s story plan for Ghostbusters 3 — saw even more upgrades take place, with the car now called Ecto-1b, including a super-sized ghost trap on the roof.
Yet, while Afterlife director Jason Reitman insists Ghostbusters 2 is still canon, the vehicle seen in his movie sports the original Ecto-1 design, with no explanation of why the upgrades were jettisoned. Making things a bit more confusing on the retcon front is that the Ecto-1 now has a gunner seat, which must've presumably been installed prior to Egon leaving the team behind, as he couldn't both drive and operate the gunner seat simultaneously. The gunner seat is itself likely a nod to the Real Ghostbusters cartoon, in which Ecto-1 did have such a device, but in-universe, it doesn't make much sense.
Lastly, Ghostbusters 1984 is clear on the fact that Ray purchased what would become the Ecto-1 for $4800, and to call it a fixer-upper would be an understatement. That would make Ray its legal owner, yet Egon is said to have absconded with it when he ran off to Summerville. Ray seems upset by that, yet apparently didn't bother to use his ownership rights to have it legally tracked down by a repossession firm. Winston recovering the vehicle at the end of Ghostbusters: Afterlife is also odd since again, Ray bought it. The only logical explanation is that at some point the team entered a shared ownership situation of Ecto-1, although that still wouldn't excuse Egon's theft of it.