Grab Key2 from the dead body in the Office.
After leaving the Sewers, head out onto Main Street. Head to the Police Station (lower right). The lady in red should spawn. If does not, leave and come back. Use the HIT command to knock her out and then take all items in her purse. Head back to Main Street. Use Key2 on the car and enter it. Press the button (lower left of steering wheel) to open the hood. The car will explode.