Let's see I'm a combat veteran Iraq Desert Storm. If the story is they were being chased and then fired upon, you may have a valid point. But, if it was an ambush attack be it from the back or as the bullet holes in windows of the business, it would suggest they were side by side again if its unsuspected and they are using auto fire they would have hit the vehicle easily. To close in proximity of one another to have the wind affect it or even bad aim.
Just like a shotgun is a great gun for beginners because its a point and click weapon the spray area is broaZd. If the eyewitness are to be believe and they let off a lot of rounds in a short period of time estimates of 10 to 20 shots fired one of those rapidly, fired rounds would have lifted paint and or pierced that vehicle no matter the rate of speed, the vehicles are traveling because it is more or less CQC(close quarters combat) shot.
Or it could be a case of a young guy not knowing the weapon he's firing, and the first shot recoil the weapon which threw the trajectory off and with each shot fired the barrel raised the site line, hence the holes in windows of business.
This is all speculation.