If any dealer fails to file the report required by Section 3.36.120, the City shall proceed forthwith to determine from the best available sources the amount of motor vehicle fuel sold, distributed, or used by the dealer for the period unreported, and such determination shall be prima facie evidence of the amount of fuel sold, distributed, or used. The City shall immediately assess the dealer for the motor vehicle fuel tax in the amount so determined, adding thereto a penalty of 10 percent for failure to report. The penalty shall be cumulative to other penalties provided in this code. In any suit brought to enforce the rights of the City under this section, the above determination showing the amount of tax, penalties and costs unpaid by any dealer and that the same are due and unpaid to the City is prima facie evidence of the facts as shown.