[ZekeySpaceyLizard]

Yes well.

That would depend on the vehicle you are driving.
But on average I would bet 20 gallons.

Neptunes current position would suggest an X,Y,and Z angle in accordance with earth being at a good atronomical coordinate of:

32, 4, 729

Thusly, if you are going 17 miles at 32mpg, then you took only about 30 minutes to do so.

Which means Neptunes coordinates are now: 32, 25, 729

So the answer would be..........21

Graphing calculators do most of the work for you.