Cheers 👍 I'm a Nikon D40 user too. I'll try the settings you mention as I definitely think I need work on some of the settings.
As for the blurring, refer to what I typed above. I've no problem with camera shake, the issue for me is finding the right settings to ensure that things like cornering photos come to life a bit more without the car being too blurred. Am I right in thinking having a very short focal length should allow me to get say, the front of the car in perfect focus while the rear is blurred on a shot like this one?:
ah, now I understand better what you're trying to achieve. Well, I'd say at that distance there is practically no chance to get parts of the car in focus and the rest not. You'd have to use a lens with very high aperture so you'd have an ultra shallow depth of field. Unfortunately at these distances the front of the car and the rear are practically on the same "DOF-plane" so they most likely be in the same focus. If you'd get very much closer and used, lets say f1/1.4 or f1/1.8 then this could be a different story.
Could you maybe post an example of what you'd like to achieve? I think most of it is actually composition, atmosphere (as you've already said) and being at the right spot in the right time. The same pictures would definitely more dynamic if the cars dragged a 20ft high dust cloud behind them, but this can't be done with aperture settings
Recommended reading:
http://www.kenrockwell.com/tech.htm (I recommend the rest of his site too, pretty interesting and amazing stuff
PS: I find it interesting how many Opel Mantas drive around there