We only use Past Perfect to make it clear to the listener what the order of events was (He crashed into a wall. He went to hospital). When we use 'after' or 'before' the order is clear, so we generally just use Past Simple. (Although it's not wrong to use Past Perfect in this case, it's totally unnecessary and a native-speaker wouldn't do it).

In this case, I say option 2 is better. Past simple and past perfect have very little variation. Option 1 would be good if it is something like 'He had driven the car into the wall so he was sent to the hospital.' Past perfect is often used with already, yet, just and even.

You can use either it depends on what you are trying to convey or what actually happened. Sentence 1 means after the car accident after he had finished drıving into a wall. He was sent to hospital. Sentence 2 leaves things a little vague and open he may have driven into a wall bounced of and continued driving, then later was sent to hospital for delayed reaction injuries like bruising and whiplash. They essentially mean the same for general communication, but for other circumstances like giving a report to the police they may ask what was it did the car stop “ he had driven and came to a halt” or “he drove and continued driving after hitting the wall”

1. After he had driven the car into the wall, he was sent to the hospital. 2. After he drove the car into the wall, he was sent to the hospital. Both sentences are equally correct, the only difference is the sentence order and what you would like to say first. He was sent to the hospital after he had driven the car into the wall. It is always better to use the simple form rather than perfect tenses since they're a lot easier to understand. This would be a better use of the past perfect since it is used to say something before another event in the past.

Both sentences may be fine but No 2 sounds a lot more natural.