Why do cars, boats, planes and helicopters break my game?

Most of those items and poses are really old and the creators have not updated the files to keep up with the game.

"Bananas_45;c-18267336" wrote:
Most of those items and poses are really old and the creators have not updated the files to keep up with the game.

Thank you. That makes sense because I bet most of them were made for the Sims 3. I've read that the Sims 3 had cars.

It may also be that they're simply too complicated. The higher the polycount, the harder the game has to work to deal with it. Some 3D meshes I've seen of cars have an insanely high polycount (for the Sims 4, anything over 10k for an object is stretching things, if it's close to 50k, the game probably won't tolerate it).

If you just want a car that loads, the "Sylvan Motor Carriage" by Alpha Waifu does (but it's very vintage looking). You can't get into it, but it loads in a lot without crashing the game.

I would be careful when looking to ensure the cc you're downloading is converted for TS4 if you're concerned the files you're finding are actually for TS3.