Math behind MPG

[dcb]

Well, it aint worth a hill of beans, but the trend for gas for the last 5 years has been upwards. Like 2.33 times more expensive now @ 4.09/Gallon. Projecting the same rate of increase would put it at $9.56/Gallon in another 5 years so maybe the 5 year figure should be more like $7.00 a gallon? But for a lot of folks it is more than just about money, believe it or not.

Current Gas Prices and Price History

[offroad1994]

again going back to the math of MPG ---

I am wondering as another post above says, why do we look at MPG, instead of gallons per 100 miles? Maybe we should consider gallons per 100 miles - per weight of vehicle? Since a motorcycle or a moped can get 70 to 100 MPG typical. Or maybe we should all look at gallons per 100 miles - per cargo space of vehicle?

Thoughts? A diesel TDI VW is a light weight high MPG vehicle, versus heavier Toyota Prius technology.

[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.

[whokilledthejams]

Originally Posted by offroad1994

again going back to the math of MPG ---

I am wondering as another post above says, why do we look at MPG, instead of gallons per 100 miles? Maybe we should consider gallons per 100 miles - per weight of vehicle? Since a motorcycle or a moped can get 70 to 100 MPG typical. Or maybe we should all look at gallons per 100 miles - per cargo space of vehicle?

Thoughts? A diesel TDI VW is a light weight high MPG vehicle, versus heavier Toyota Prius technology.

MPG or Gal/100mi per person would be more useful. The weight of a motorcycle vs. a suburban is irrelevant if each is only carrying one person, because, in effect, that person is consuming the fuel. On the other hand, a very large SUV with a full load of passengers is relatively efficient. 14mpg with seven people becomes 98mpg per person, thus making a 70mpg bike not sound so good.

Correct me if my math is screwy, of course.

[ebacherville]

OK how about this and proving hypermiling is worth it,
I have a 2005 chevy colorado pickup, it has no mods to it, I purchased a scan gauge for it, I can consistently get 35 MPG out of it.. the truck is a 25mpg High way rated truck. and I used to get 25mpg with it before the scan gauge and hypermiling techniques, I calculate that at 15k miles a year it will save me $688 in gas savings with gas calculated at $4 a gallon.

The scan gauge only cost me $160 so in the first 3,000 miles the scan gauge paid for its self, after that its all gains in my pocket.

I calculate making a Areo topper from foam and fiber glass would cost me about $500 would it pay for its self, I'm sure it would easily pay for its self with in a year.