Both are correct.
 Bill said that his neighbour had a new car.
 Bill said that his neighbour has a new car.
Present tense is often used in reported speech when what was said is reported soon after it was said. Like this,
Bill: My neighbour has a new car.
Sam: What was that? I couldn't hear you. A bus went by.
Pat: Bill said that his neighbour has a new car.
Does that help?
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