@centrox,
centrox wrote:
All three are OK grammatically; 1 means you personally saw a car drive past a stop sign without slowing down; 2 and 3 mean you saw evidence or proof that a car had driven past a stop sign without slowing down. Your title should be "Are any of the following sentences incorrect?"
Quote:3) I saw a car drove past a stop sign without slowing down.
I think 3 is dubious. Although the words "see" or "saw" are often used loosely to convey general meanings of understanding, second-hand information, or general impressions, that intended usage is not always clear. Literally "saw" refers to one's own past visual sense impressions.
If you intend it to mean "I heard that," "I read that," "I am informed that," or something to that effect, I think you should use such words, unless the context otherwise makes it clear. Maybe this isn't, strictly speaking, a "grammatical" error, but I think the word choice renders the sentence ambiguous and/or incoherent.