sndein Well, the suction cups show up in the unshaded reference, so they should at least be partly 3D to match the outline. But I'll have another look and take your suggestion into consideration. So far it's all vertex colouring, btw, just like Carrot. (only Carrot's vehicle has textures)
I'm modifying Keith's Racing Kart to use as the vehicle. As far as I know it hasn't been used for STK yet. And the tires seem suitable for a beach, where squids are most likely to drive their car.