I am sorry to hear this, and I certainly hope your friend is OK, but you don't really expect a police officer to alter his report once it has been submitted simply because one of the subjects in the report says it should be altered do you?
Witnesses lie, and lie frequently, they are also often wrong or simply have a different perspective. Of all the evidence one can gather, eye witnesses have proven to be the least reliable. On the other hand, if the officer misrepresented what you said a call or visit to the station to speak to the supervisor could be in order. I would.
A shooting would not be handled or investigated by detectives in the same manner that a parking lot fender bender with a slight injury would be by a beat cop. There is a reason for this and protocols in place for lethal force incidents. On the other hand your misgivings could be perfectly valid in a more rural area. Good luck with the quality of the investigation in one of our neighboring counties to the north. One Sheriff and one deputy. Besides jail staff that is it. If the sheriff calls the highway patrol to help (he often does) you will be in better shape.
Perhaps the other car was modified in some way? Non standard tires for more traction? A high flow air cleaner indicating a propensity to drive recklessly? A Nascar sticker? Your lawyer could use these things to ruin him in court apparently.
"A Liberal is someone who doesn't care what you do, as long as it's mandatory". - Charles Krauthammer