You should certainly try a few panning shots as they look great, having seen a few posts on here about panning you should use a slow shutter speed anywhere from 60 to 100 and manually focus on a section of the road that the car will pass. I’m sure others on here will give loads of advice, a monopod would be very useful for panning.
I know its over now but next time try panning,head ons,front 3/4’s but whatever you do, dont put yourself in a dangerous position, especially at rallies