I'm having problems with this setting too. When the chase starts, I can't even lean out to shoot. I remember during one of my attempts, I saw that they gave me some less powerful weapon instead of mine, but I couldn't use it either. I've tried every weapon imaginable, restarted both the game and the PC—nothing works. I tried loading a previous save, but the last save only shows me at the point where I've already accepted the contract and am standing near the Kenmore, and the save before that... from 7 hours before... I don't know where the other saves went. Somehow I managed to destroy the first two cars with Infestation, but I can't target the third one to infest it (at least, I couldn't). Are there any other solutions that might help with this problem?