[Peakoil] Bus efficiency

[Alex P]

Hi fols,

Reading Heinberg's Oil Depletion Protocol, on p46 its says a bus filled with
passengers uses 84% of the fuel that would otherwise be collectively used to
go the same distance in private cars. The source for this is

http://apta.com/research/stats/factbook/documents/energy.pdf

However the efficiency of the bus is given as 3.65 miles per gallon
(diesel). Assuming the average US car is 22 miles per gallon (gasoline)
(p31), this means it should take only 6 passengers for a bus to match
private cars. Every additional passenger it gets better. To get 84% of the
cars' fuel use you only need 7.2 passengers.
For 30 passengers the bus uses only 20% of what the cars would.

It's not in the errata:

http://www.oildepletionprotocol.org/thebook

Does anyone have better numbers?

Alex