Last summer I went to Europe with my family, and I came across this car. It looks like a Zimmer, but it's much longer than most Zimmer's. Can anyone tell me what car that is?!

Cool car! I don't think it's a Zimmer, but a similar conversion riding on the Neo-Classic-wave. The front fenders remind me of the CMC Classic Tiffany, but it isn't one of these either.

I'm planning to start a major Neo-Classic identification project at some point here on IMCDB and once the time is right (to be honest, I'm a bit afraid on my own behalf of opening that can of worms...), I will look into this one as well - that's all I can do for the moment.

I don't know many that were based off a Crown Vic/Grand Marquis 4-door chassis from the mid-late 80s. Most used a 2-door chassis of a Cougar or Regal from that era.

Yeah, that's what bugs me either - a sedan, but no Lincoln or Cadillac. This might well be something coachbuilt by Rage (= Knudsen reloaded) or Baroque Motorcars or Elegante Coachworks Ltd. of St. Louis, Missouri.

Excalibur Phantom?

https://c1.staticflickr.com/9/8596/16106708555_e1cb0caa3a_b.jpg

https://c1.staticflickr.com/1/919/27736841248_75eb1f8ec7_b.jpg

https://rmsothebys.com/en/auctions/DF06/Michigan-International-Fall-Classic-Car-Auction/lots/r184-1990-excalibur-phantom/207925

The first one looks like it's based on a Cadillac,

second one a Chevy Caprice,

Third one is a Chevy Camaro base.

Third one is a Johnson Phantom, the OP car and the first two are one of the many built by smaller operators, quite possibly on used cars even.