The argument that some are making in his favour is that, when the car initially starts moving forward, he did not realise the car was turning right or how slowly it would go. They say that, for all he knew, Renee was going to floor the throttle and drive straight at him. So, they argue that the first shot was unavoidable, because by the time he realised he was in on danger, he was already committed to firing.
The counter argument is that he had watched Renee put on full right hand lock and had seen the wheels turn accordingly, so he knew where the car was going.