"Slambram" wrote
If you
really want to know, get a fuel flow meter or sometimes you can plug
into your fuel injected engine's diagnostic port and get this info
with the right equipment.

They also make fuel flow meters that can link with output from common GPS
units for miles per gallon read-out . I can't remember what that link is
called - all I remember is that my (fairly old - maybe 10 years) GPS doesn't
have it. Of course, this stuff isn't cheap, but for a gadget freak, it
would be worth it, I'd guess.

G