For the first question, I think the "their" is ambiguous. It can refer both to cars and manufacturers.
For the second, the statement is a general statement. It's stated as a fact. When it comes to facts, GMAT uses simple present tenses. Using 'has failed' is wrong for this case.
For the third, using 'and' means that the ban only applies to foods that contain ALL of these restrictions. Using 'or' is correct and idiomatic in this case. (I believe you got this in OG12
Didn't mean only GMAT uses simple present tenses. It's the correct verb tense for expressing facts.