Doesn’t make any difference at all.
If he was 1 foot from his vehicle or 10 miles form his vehicle, when he was assaulted and his life placed in danger, he then had the right to defend his life.
Even if Zimmerman followed Trayvon at a distance of one foot and called him every name in the book, Martin had no right to assault him. As soon as martin did that he became a violent criminal.
IF Z was assaulted as he says, then you are right, and WHERE it happened is irrelevant, and I do believe, fervently, that he was assaulted as he says. BUT, if he was near his vehicle, that gives TREMENDOUS SUPPORT to his story, and helps him tremendously. Remember, neither you nor I are on the jury, unfortunately.