Q: How many (US) gallons of 87 octane gasoline can be made from one barrel of crude oil?
A: 19.5

Q: How much does the average gas station pay to buy a gallon of gasoline from an oil company?

A: Retailer (gas station) profit is about 1 to 5 cents a gallon. So they pay the posted price, less that and less taxes (federal, state, local).

Q: I did some simple calculations, and the numbers don't seem to make any sense. Let's assume that the price of crude oil is $37.00 per barrel. At 19.5 gallons of gasoline per barrel, this means that a gallon of gasoline in its crude oil form costs $1.90. Yet, when I pump it into my car, I'm currently paying $1.76 per gallon. This means that the gasoline is losing 14 cents per gallon in value when going from ground to gas pump. This must mean that everyone involved in transporting and refining the oil and gasoline must be marking down the final price of their finished product. Companies mark up, not down. Obviously, there is something wrong here somewhere.

A: The 42-gallon barrel of crude oil makes about 19½ gallons of gasoline, 9 gallons of fuel oil, 4 gallons of jet fuel, and 11 gallons of other products, including lubricants, kerosene, asphalt, and petrochemical feedstocks to make plastics. [See also this EIA page] That adds up to more than 42 gallons because of something called "refinery gain" - the processing and chemical changes decrease the density and hence increase the volume of the refined components. So, crudely (pun intended), a $37 barrel of crude represents about 88 cents a gallon to start with. That 88c represents the cost of production plus producer profit. Go up from there.
[link to www.gravmag.com]

PUNN? 37 A BARREL === 88C? A GAL PLUS PROFIT.. A LOT OF PROFIT