Subordinate Clauses and Participial phrases?

[dtbtb]

My tutor taught me that sometimes I can reduce these sentences:
Cars that were made in China are unsafe.
Cars that contribute to pollution should be banned.
into these two:
Cars made in China are unsafe.
Cars contributing to pollution should be banned.

Also my tutor also taught me this:
Change:
The high cooking temperature alters the molecular structure of the oil, which make the food unhealthy and difficult to digest.
into:
The high cooking temperature alters the molecular structure of the oil, making the food unhealth and difficult to digest.

And in my recent essay, I used this method.
Instead of writing:
The success of restaurants which convince individuals to consume relies on several techniques.
I wrote:
The success of restaurants convincing individuals to consume relies on several techniques.


I have never figured out how these techniques work. I read some grammar books and thought the shorter sentences were related to participial phrases, but I wasn't 100 percent sure. Could you confirm the modified versions have participial phrases?

[Soup]

Take a look here Reduced Relative Clauses.

[dtbtb]

Thank you! That helped a lot!

[Soup]

You're most welcome.