The 6th image works the best for me with Cammish leading Ingram as it tells a story. This one isn't cropped too tightly and you can see where the cars are on the track and they have some space to move into.
For the first one, you really need to see the whole car especially when you can't see the driver. From the shadow, it looks like you were shooting into the sun, hence the shadows are very dark and there's little to no detail in the wheels etc. The last Cammish one is much better in this respect.
The 3rd one (Taylor-Smith) doesn't work for me, as it's at a too steep an angle to be natural (the tyre wall in the background gives this away) and there's barely any blur in the wheels to suggest movement (too high a shutter speed) so it looks a bit static/parked.
The second to last one (Rowbottom) looks good, but the bright fence posts at the bottom are a bit of a distraction so I'd try to crop those out or remove them in photoshop.
