Usar vs Uso

[WowRly]

The conjugation of the verb "usar" for "yo" is "uso": "yo uso."


Why does the following sentence not use "uso": "No, I don't need to use the car."


"No, yo no necesito usar el carro." Instead of the incorrect, "No, yo no necesito uso el carro."

[Rusty]

In your English example, the verb is not 'to use'; it is 'need', as in 'I don't need'. Using the color green to flag the verb and the color plum to mark its object, the unconjugated English sentence becomes 'not need to do something' («no necesitar hacer algo», in Spanish). The 'to do something' piece answers the question, "What is needed?"
If 'what is needed' is an action instead of a noun, the English full infinitive ('to use') must be substituted for the 'to do' piece. A full infinitive is never a verb; it acts as a noun (the verb's object, in this case).

It works the same in Spanish. The infinitive 'usar' is substituted for the 'hacer' piece, the object of the verb becoming 'usar el carro'.
The first person conjugation of the verb is 'no necesito' (the subject pronoun 'yo' isn't a requirement in this case).

I hope that helps.

Welcome to the forums, by the way!

Below, I have colored the verb in green and its object (what is needed) in plum.

No necesito usar el carro.

[WowRly]

A detailed answer--Thank you!