[lunarhighway]

i think this sort of calculations are only really valid if you're looking to buy a new vehicle, a more fueleficient vehicle might cost more and therefore even with the better milage be more expensive in the end, at the end of the day everyone must make sure all bills are paid. and we all have a buget.

on the other hand where i live fuel is about double the price of the us, so all saveings are doubled as well, small changes might pay of faster for me that for somone who's got cheap fuel... the more expensive gass gets the more carmakers and gassavers alike can invest in, or in other words a mod that might not pay in the cost vs saveing department, might start to make sence when fuel prises increase a lot.

personally i find L/100km (gallons/100miles) an easter form to work with than mpg
generally people tend to use the same trajectory on a dayly basis so l/100km or PGkM
makes it easier to visualise how much fuel you saved and to calculate your direct cost per distance traveled...

miles per gallon only seems usefull when you're out in the desert and wonder if you'll make it to the next fuel station.... wich is perhaps why this in the us where distances are traditionaly more vast, as opposed to europe where everything is more dense.