By car, in my car, etc.

Prepositions are always a bit tricky in English.

Payman asks: Which of these sentences is correct?

"I go to work by my own car." / "I go to work in my own car."

The correct sentence is: "I go to work in my own car."

You can travel by car (or another vehicle) in a more general sense:

I usually travel by car.

My parents are coming by train.

My sister hates traveling by plane.

But notice how the prepositions change when being personal or specific:

We did our homework on the train.

My parents said they ate on the plane.

I took off my sweater in the car.

Some other equivalents:

I came by car. = I came in my car.

I came by train. = I came on a train.

On and in can be used the same way in some contexts:

We met on the train. = We met in the train.