I also have a Yakima bike rack on my van, but on the rear hatch, down in
the "hole" the van creates in the air-stream.   Mounted back there In that
area, I've seen no significant difference in fuel economy...even when I have
3 bikes and 5 or 6 detached spare wheels mounted.  The hatch-mounted rack is
easier to use than a roof rack, also...though with bikes mounted,  the hatch
becomes more difficult to lift and it needs a prop to stay open reliably.
Also, when you travel dirt roads, the low pressure area behind the van
really creates a 'dust vortex'.  Bikes mounted on the rear get quite filthy
in a short time.  Since that hatch-mounted rack is not really a factor in
gas consumption, I normally just leave it on there, ready to use when I have
no room inside for my bikes.

   There is nothing 'cheap', nothing silly about trying to spend effectively
on  fuel, in my humble opinion.  Those 2 miles per gallon that I discovered
can be saved by removing my roof rack, if I don't need it, that might seem
petty...but my math shows me I'll have saved $600 (+/-) by 'paying just a
little attention'..... I can better spend  $600 a year else where.  2mpg
saved is (very roughly) 10% of my verified gas mileage.  I log   appx. 30k
in my van every year.  That 10% is 3000 miles, or about 150 extra gallons
burned, and gasoline costs $4/gallon now.  I guess I can take a few minutes
to remove and stash my roof rack to save $600 or to get an additional 3000
miles of traveling in. (Portland, Or. > Baja and back?)

On Tue, Oct 25, 2011 at 4:19 AM, Stephen Grisanti <bike2vcu@yahoo.com>wrote:

> I was a rep in the bike biz for about 15 years, a job that practically
> demands a full-dress roof rack.  Over the years I used three different racks
> on a Nissan Sentra, a Nissan pickup with a shell, a Ford Aerostar minivan
> and a Mopar minivan.  Interestingly, the two vans experienced the greatest
> sensitivity to gas mileage with the racks installed.  Averaging 1,000 miles
> a week it was not too much work to remove a rack if it was not going to be
> needed that week in order to save a little gas, and that was when gas cost
> 1/3 to 1/2 what it does now.  Wind noise was an issue as well.
>
> Stephen
>
> --- On Tue, 10/25/11, Danny C. <bruiserbabie@YAHOO.COM> wrote:
>
> From: Danny C. <bruiserbabie@YAHOO.COM>
> Subject: Re: Aerodynamics related to fuel consumption (for an 84 tin top)
> To: vanagon@GERRY.VANAGON.COM
> Date: Tuesday, October 25, 2011, 12:18 AM
>
> Seriously!!! your worried about what drag there is on a roof rack. WOW!!!
>