if your budget will around some $300-$900 then it very good for camera.
Referring back to the initial few posts in this thread:
Motorsport/ Action means fast movement (unless said motorsport involves parked cars)The following is a rough guide of choosing the right camera to your specific needs!!
----------The camera must have a high shutter speed (to capture sharp unblurred images)
----------Ability to take continous shots
----------Large frame rate (eg, 6 upwards is quick)
----------Large autofocus points (the more the better if you wanna autofocus a subject)
-Low light/night time shots
----------Low noise at high ISO levels (once again ISO, noise etc is explained in the sticky thread)
Fast movement requires fast lens if light conditions are not ideal (i.e. cloudy, early morning, late afternoon).
Invest in good lenses too if possible, it'll go a hell lot of a longer way than a good camera body.
Something with f/2.8 as a minimum would be a good start (can be expensive, but third party manufacturers like Sigma, Tamron, Tokina make excellent lenses that aren't pricey)
Big aperture is also sometimes desirable for portrait shots (when you want that creamy blurry background, isolating the subject)
Good gear will help you achieve better results with less work.