A couple of ways I'd try. I don't know exactly what the livery looks like. But to do a curved stripe I'd try the thin curves that look like a ) first.
If that doesn't work then this; if your car's body is a standard color, not
Specialized then you can place a thick stripe in the general shape you want then whittle out down with other shapes matching your body color. Example, take a circle, squash and stretch and tilt it to the curve to "cut out" the curve your looking for.
Hopefully that helps.