This is yet another thing people who haven't been actually been at the site don't understand or refuse to take into account. That particular area of the plaza is a triangle with 3 streets and on a hill. The limo turned left in front of the book depository and immediately travelled down the hill and began a curve away from Oswald. The car was not the only moving target but the passengers were also moving to avoid getting hit, jumping/startled by the noise, and/or jerking and slumping over. And on top of everything else, Oswald would have had to be leaning out the window because the car had already passed. If anything, Oswald had a much easier shot when the car was still on Houston Street before turning onto Elm. He would have had a minute or more to sight in and fire straight on and the car was headed directly towards him. Taking the hit on Elm just doesn't make sense.