Who does need/Who needs

The first one is correct. The second is incorrect.

Consider the example; Who needs a new car?

This is a grammatically straightforward question. The subject is "who", the verb is "needs" and the object is "a new car". Adding the verb "does" in a normal question is simply wrong.

However there is a complication. (In English there is always a complication). To make this a negative question requires the helper verb "does". I think this might be the cause of your confusion.

This is also correct; "Who doesn't need a new car?".

For some strange reason in English, to make a question negative you need to add the "does" into the sentence ("doesn't" means "does not"). But this is only for negative questions.

You can use does to add emphasis in certain situations, e.g. Who does need a drink, and who doesn't? You might use this with any verb, in a situation where some doubt or confusion has arisen. Otherwise for a question like that we use who and the 3rd person singular. Who needs a drink? Who wants a sandwich? Who has a camera?

When speaking you would emphasise the word 'does', and when printing you might use italics or bold - who does know where the hotel is?