There are a couple of ways you can get results like shot 2...
Firstly, you can have two cars travelling at exactly the same speed, on a perfectly smooth surface, without even a slight variation in direction. Take a photo of the subject car from the first with a long enough shutter to blur the background - This is obviously damned hard work.
The other way is to use Photoshop/Photo-PAINT or any similar app... Firstly, you cut the subject to be kept sharp out to a new layer; next you create an adjustment layer/mask to the 'shape' you'd like to project add a gradient to give direction to the effect, then feather the area so it's not abrupt. Blur using a convetional blur, motion blur or smart blur (to get the effect to taste), and then put the layer with the 'sharp' subject back on top - et voila!
...Anyway, waffle over... They're some really nice shots! Good work :thumbsup:
Regards,
Rob.