Great question, Rambo. I was curious myself... it's just one. Albeit, one hulking mo-fo of a hamster with a wheel of parm, a bottle of nebbiolo and a pack of Camels.
Guido the hamster is certainly frugal... combined mpg average over a twelve hour drive thsi weekend was right at 38... and for a roughly 20 minute stretch I was able to average 47 which is well above the EPA suggested range, especially for the Auto-6.