The shine is definitely a nice feature, but it hasn't been done quite right. I think the shading around it needs to be more textured, like the pipe from SMW. Right now, it looks like the light source is above just is directly hitting the center of the kart. Try to make it look like the light source is coming from the same direction as it is with the rest of the karts. But remember to make it still look cylindrical. (Sorry if I didn't explain this right. I'm mainly just trying to say, make the shading more like the SMW pipe.)
Also, the beam in the center of the kart has no shading.
Also, the beam in the center of the kart has no shading.