weight loss $/lb on a truck calculation

[miket]

I' watching max weight of my dads truck to make sure it doesn't go much over the payload capacity. However for economic reasons I wonder how many $/lb in a weight savings is worth? He drives 20K per year 3/4 highway. Alot of the stuff that I have to add to the truck for utility comes in either steel or aluminum.

[RobertSmalls]

Well, the amount of energy you'll spend hauling that around, excluding braking, is:
distance driven * CRR * 9.81m/s² * mass
divided by the efficiency at which you can produce power.

Then double it to account for braking. Then figure adding weight causes you to downshift and produce power less efficiently.

I figure you're looking at about 10gal/yr per 100lbs.

[miket]

Does that include the 5k year city driving?

[RobertSmalls]

*shrug*

You're not going to get a very accurate answer without running it through a sophisticated computer model based on his particular driving style.