"the Ford Explorer has an 18 (US) gallon fuel tank"
Because of the distances involved here Out West[0], many (most?) jurisdictions equip their patrol vehicles with extended range tanks. I don't know if Fremont does or not (it's only 75 square miles or so), but given the gridlock they experience twice a day, 5 days a week (+occasional weekends), it wouldn't surprise me.
[0] Wherever that is ...
Biting the hand that feeds IT
