Car ferries

Carvair was built out of DC-4. It kept the wing and engines, but the nose was replaced with a bigger one, including nose door and cockpit up in the hump above nose door – the prototype for 747.

There are said to be a number of propeller car ferries.

Can widebody jetliner holds be used as car ferries? Like B747, B767, A380?

I gather that the holds are low. Maximum height of 163 cm, for all widebodies between 767 to 747.

This means that sedans can be put in holds, and so can limousines – but SUV-s and most crossovers are too high. Rolls-Royce is barely low enough.

Do passenger airlines normally offer car tickets?