Figure 10 lbs drag  per 1,000 lbs of weight on your tires.
It's fairly independent of speed.

Thusly:  300 lbs less load = 3.33 lbs less drag (rolling component)
Your aero drag is negligibly affected.

Randy Bergum
1990 Carat

> [Original Message]
> From: Gabriel Ross <gabeross@ORO.NET>
> To: <vanagon@GERRY.VANAGON.COM>
> Date: 8/17/2005 9:36:45 AM
> Subject: Re: How much fuel efficiency gained by shedding 300 lbs?
>
> Well, maybe it's not that germane for us vanagon owners, but ol'
Einstein's
> equation (E=MC squared) (don't know how to make my computer put that
little
> 2 above the C) is the basis of this. So that's Energy equals Mass times
> Velocity squared, and since the mass is a constant regardless of the
speed,
> you can easily see why it costs more to go faster. For the math
> impaired,  here's a chart:
>
>          E = M(25 X 25)  625M
>
>          E = M(35 X 35) 1225M
>
>          E = M(45 X 45) 2025M  (that's over 3X the energy required at 25
mph
>
>          E = M(55 X 55) 3025M
>
>          E = M(65 X 65) 4225M
>
>          E = M(75 X 75) 5625M  (that's 9X @ 25 mph)
>
> So, going 75 takes almost double the energy as going 55. As fuel prices go
> up, this is more and more relevant. We're lucky that we've got a built-in
> governor, eh? The "eh" is for the Canadian list members, since I didn't do
> kph. :>)
>
> Gabriel
>
> At 10:35 AM 8/17/2005 -0400, Roger Sisler wrote:
> >I just heard on the radio that driving over 60 mph is like paying .15
cents
> >for each mile per hour over this figure.If gas is $2,50/gallon(dont we
> >wish), driving 75 mph is like paying $4.75/gallon.I havent tried this
> >myself,but it think it might be a bit high.75mph is a place I only
approach
> >by passing slower vehicles,and this only takes about 5 minutes.