My car is on fire. What is the verb

It's a linking verb, not an action verb.

http://grammar.ccc.commnet.edu/grammar/verbs.htm#linking

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list 10 examples of physical action verbs

The verb in the sentence "My car is on fire" is "is."

To identify the verb in a sentence, you can follow these steps:
1. Identify the subject: In this sentence, "My car" is the subject.
2. Identify the action or state of being: In this case, the action is "on fire."
3. Determine the verb: The verb is the word that expresses the action or state of being. In this sentence, "is" is the verb.

So, in the given sentence, "is" is the verb.