I somehow found out by myself how to add motion blur.
Just select objects that you want to have motion blur on, for ex. wheel (one wheel,
WITHOUT BRAKE CALIPER), then go to "Motion" tab and Press button: Add key:
Rotation. Then go to next frame, either by clicking on > in that frame line in bottom
or I guess by clicking . button on keyboard, then add rotation key again but this time set rotation axis (and maybe in first frame you had to set it, dunno, just try) and set rotation angle, while changing it you'll see how wheel rotation changes.
After setting these things up, go pack to frame #1, go to V-Ray camera properties and enable Motion Blur. And don't forget to increase shutter time, because these are basics from photography, longer shutter time - more blur
Good luck