When do we use “had had” and “have had”? [duplicate]

I have seen several sentences in English where some writers have written had twice in a row. I am a bit confused about when the grammar calls for using had had.

For example:

• I had had my car for four years before I ever learned to drive it.
• I had had a bath, but I didn't feel clean, so I had a shower.

There's no special magic with "had had", they don't really go together as a pair anymore than "had wanted" go together.

So don't worry so much about how to use "had had" as a unit of grammar, they will come together naturally when you want to express the verb 'to have' in the past perfect.

Let's consider a different verb for a moment like "to want". Suppose that at sometime in the past I wanted to do something, but I don't want to do it at present. You might say, "Last year I had wanted to buy a new television, but now I don't have the money."

Now let's use the verb to have instead of to want. Suppose that at sometime in the past I had something, but I don't have it at present. You might say, "Last year I had had the idea to buy a new television, but now I'm not sure I want to."

In most cases, have is used as an auxiliary verb. Examples of auxiliary verbs,

I have to go to school.
I need to go to school.
They have eaten breakfast.
She has never played football.
He does not eat breakfast.

However, the verb have is also often used as a proper verb (as opposed to being an auxiliary verb) in place of proper verbs such as eat or partake.

I am eating breakfast.
I have eaten breakfast.
She has never indulged in sex by the time of her 18th birthday, today.

can be translated to

I am having breakfast.
I have had breakfast.
She has never had sex by the time of her 18th birthday, today.

Referring to a past time of reference,

She had never had sex by the time of her 18th birthday, three years ago.
She had had sex by the time of her 18th birthday, three years ago.

Another mode of use is its auxiliary use to encapsulate a perfected/completed participation.
e.g., have experience,

Do you paint houses?
Are you familiar with painting houses? Do you {have experience} painting houses?

I am hiring her because she does {have experience} painting houses.
I am hiring her because she has {had experience} painting houses.
I am hiring her because she has {fulfilled experience} painting houses.
I am hiring her because she has {had painted houses} before.

I hired her because she did {have familiarity} programming in C#.
I hired her because she {fulfilled familiarity} programming in C#.
I had hired her because she had {had familiarity} programming in C#.
I had hired her because she had {acquired familiarity} programming in C#.

Then why not simply say,

I had hired her because she had {familiarity} programming in C#.

What is the difference between saying

Since he had {had the experience} of being kidnapped, he did not panic.
Since he had {gone thro the experience} of being kidnapped, he did not panic.

vs

Since he had the experience of being kidnapped, he did not panic.

?

The difference is in the temporal displacement of the observation.

When you say

Since he had the experience of being kidnapped, he did not panic.

You meant to say,

When he was kidnapped in 1980, he did not panic because we know that today he had experience of being kidnapped before 1980.

When you say,

Since he had {gone thro/had the experience} of being kidnapped, he did not panic.

You meant to say,

When he was kidnapped in 1980, he did not panic because we know that in 1980 he had {had the experience} of being kidnapped before 1980.

Therefore the difference is in saying,

• we see that today, he had experience of being kidnapped before 1980.
• we see that in 1980, he had had experience of being kidnapped before 1980.

Both sentence structures convey the same message, but differs in when the observation was made about his having acquired the experience. But sometimes, this difference is not trivial. For example, in a trial murder.

The prosecutor asks:

What did you think was the state of his mind on the night of the murder three months ago, Dec 24th?

Defendant replies

He had hallucination before he was murdered three months ago.

Prosecutor irritatedly responds:

I am not asking about any hallucination he had on Dec 24th.

Defendant replies again

He had experience of hallucinating before he was murdered on Dec 24th.

Prosecutor, still annoyed

I am not asking what your opinion is today of his past-experience prior to Dec 24th. I am asking about what you had observed on 24th Dec. about his past-experience.

Defendant complies

On that day, 24th Dec, he had {had the experience} hallucinating since childhood.
On 24th Dec, he had experienced hallucinations since childhood.
On 24th Dec, he had had hallucinations since childhood.

Cascaded temporal projections
The perfection of participation can get more complex with a cascaded temporal projection ...

Prosecutor asks again,

Then what about what you had remembered on 24th Dec, about an incident on 20th Dec?

Defendant responds with precision
(temporal displacement of defendant's observation to 24th Dec,
but temporal displacement of deceased's status to 20th Dec):

On Dec 24th, I had wanted to teach him because, I had believed that the deceased had

{  
  never had {experienced satisfactory sex}  
  by the time of his birthday on 20th Dec
}.  

Which can be translated to,

On Dec 24th, I had wanted to teach him because, I had believed that the deceased had

{  
  had {experienced unsatisfactory sex}  
  by the time of his birthday on 20th Dec
}. 

Which can be translated to,

On Dec 24th, I had wanted to teach him because, I had believed that the deceased had

{  
  never had {had satisfactory sex}  
  by the time of his birthday on 20th Dec
}.  

Which can be translated to,

On Dec 24th, I had wanted to teach him because, I had believed that the deceased had

{  
  had {had unsatisfactory sex}  
  by the time of his birthday on 20th Dec
}.  

Using your original sentences as example
Temporal displacement to present:

I had my car for four years before I ever learned to drive it today.

Temporal displacement to last year:

I had had my car for four years before I had ever learned to drive it last year.