The amount of gallons of gasoline your vehicle will need to complete a 1,000 mile road trip will depend on the miles per gallon your vehicle gets.
But lets just assume your vehicle gets 28 miles per gallon so if your vehicle uses a gallon of gasoline in 28 miles then you would need at least 36 gallons of gasoline to complete the trip one way.
Assuming your cost of gasoline is $2.25 per gallon that would mean you would pay $81.00 in gasoline to make the 1,000 mile trip.
If your vehicle got 15 miles per gallon then you would use around 67 gallons of gasoline for that same 1,000 mile distance.
So at 15 miles per gallon and your gasoline cost was $2.25 per gallon you would pay $150.75 in gasoline.