Unfortunately, there is no quick filter to do it. I used a pen tool to outline each bit, then changed the pen thickness for different parts of the car (i.e. size 3 brush for outline, then 2 for larger details, then 1 for smaller details).
Using the pen tool means you can get curved lines and you can also use it in the next step of colour fill. So, you end up making lots of paths (around 200 in total) and layers (also around the 300 mark).
Great job tooning that car! I'm very interested in how that was done. I wanna try my own hand at tooning some cars. The problem is, I have no idea how. Is there any good tutorial site that you might know of that teaches me how to toon a car? Thanks so much in advance! Cheers.