No person shall operate, nor shall an owner knowingly permit to be operated upon any highway any vehicle required to be registered and titled hereunder unless there shall be attached thereto and displayed thereon when and as required by this chapter a valid registration card and registration plate or plates issued therefor for the current registration year and unless a certificate of title has been issued for such vehicle, except as otherwise expressly permitted in this chapter or Iowa Code chapter 321. (2008 Code § 17-98)