True, but how many gallons of diesel do you get from a barrel of crude oil?
It varies considerably depending on the quality of the crude.
From American Petroleum Institute (API) statistics an average barrel (42 gallons) will produce 46% gasoline, 22% diesel, 10% jet fuel, 5.5% heavy fuel oil, and the remaining 16.5% would be everything else including lubricants, asphalt, petrochemical feedstocks, etc.
Generally speaking though, most crudes yield between 10% to 30% diesel and most refineries produce in this range but there can be significant deviations. North Sea Brent produces about 15% to 16% diesel range material. (source)