I've been meaning to comment here for quite some time and have only just gotten round to doing it...
Your panning is pretty much spot on, the car is nice and sharp and they look great. Particularly liking the most recent shot as it's very nicely composed and has some great vibrant colours.
I'm now going to give some C&C if you don't mind. My first comment would be that variation is the spice of life, it appears you've gone to the effort to do various different compositions and what looks to be different sections of track but from a viewers perspective they all look relatively similar. Most the shots seem to be side-on panning shots, which whilst they are great, I'd like to see some more action. Perhaps try to experiment with some slower shutter speeds for the pans and then do some action shots of the cars racing around the corners with the rest of the pack. Also try getting some front end shots of the cars or front 3/4 shots.
At the moment it's also quite difficult to get a sense of location, a lot of the shots seem to have the same 'green, tarmac, car, grass, armco, fence' pattern which makes the shots look the same - even if they aren't. Perhaps try to either isolate the car from it's surroundings completely (full frame style) or show more of the background but with a higher shutter speed.
I don't mean any of this in a particularly negative light, but I just thought I'd give some constructive feedback which might actually help!
On the RAW v.s. JPEG matter, I used to shoot all my motorsport events in RAW (I was using the 350D at this point) and I was fine with doing so it was a good way to make sure that if I slightly messed up the white balance then I could fix it relatively easy in Photoshop. However, when I started to become media more often I ended up ditching RAW, not because I wanted to particularly (I still prefer that working method) but because it's simply too time consuming. In the couple of jobs I've had I've needed to have the pictures done within an hour or so of the race finishing which RAW doesn't lend itself too.
If your not in a rush to get the images out and online as quickly as possible and you have the HDD space I'd probably shoot RAW. It gives you a little bit more flexibility and lets you learn a lot about what kind of white balances suit each situation. But if your in a desperate rush to get your images processed as quickly and efficiently as possible I'd say stick to JPEG.
But that's just my opinion.
