Okay skeptics, now take a look at page 5 of the following document:
http://www.petro-canada.ca/pdfs/inve..._Q1_2008_E.pdf
This is Petro-Canada's Q1 2008 Earnings release. On page 5 is a breakout of revenue/expenses and earnings of all of their business segments (Aka Segmented Income Statement). Check out the Downstream segment which contains their retail gas stations and refineiy operations. Look at the Sales from customers line and then the "Crude Oil and Product Purchases" line and the "Intersegment Transactions" line which means purchases of oil for their downstream operations directly from their upstream operations. If you take the difference between the revenue and those two expenses you get their margin before accounting for the costs of refining and selling (which is denoted as "Operating, Marketing, and General").
Now take a look at the bottom line "Net Earnings(loss)." Notice that in Q1 2008 that of Petro-Canada's $3.7 Billion in downstream revenues which includes retail items they only made $184 Million compared to a profit of $1.076 Billion with a B for all segments. The margin on their downstream segment is very small compared to the Upstream side of things. That is where the Real money is made. So yes money is being made, but it's not really on the retail side of things.