3d print car models

How do i mae car models so i can print them?
i have a couple of car models that when i put them on the slicer some layer just dont want to be printed.

It happens with almot all the car models i find of cars.

any help?

https://preview.redd.it/e06q1xk1c1pd1.png?width=771&format=png&auto=webp&s=f3d5dcb82184324aecdd64feff1bd2e9a6c04c64

https://preview.redd.it/a04nkao2c1pd1.png?width=837&format=png&auto=webp&s=add9238b7493d39f814870aca92f599a5797b6ef