Then I'll answer, although the car's intended purpose would dictate the answer. Assuming we are talking about the Truck (after all, that's what the thread is about), I'll Say Street Car (my truck) Criteria:
Run on pump gas
cruises 55 mph on a 85* day for 1/2 hour without overheating
drives and races on D.O.T. tires
Plated and insured, and can go by a cop without being pulled over (EXHAUST!!)