baddad,

Antidotal evidence is fairly useless. If you look at the post in this thread alone, you will notice that individual results vary widely. I have seen claims in previous post for vans similar to mine as high a 18mpg. Some people will state the best mileage that they ever got as being the norm. I did not. Driving conditions and driving styles make a lot of difference in mpg as well.

You said you put on new tires and wheels that lowered the van 1" to 2", yet your mileage has "never varied off the 11-14 mark since new." That shoots your theory in the foot. Why didn't your mileage improve? Did you correct your speedometer to reflect the new tire diameters?

Some of the newer style high tops could improve airflow over the top. Maybe. You would be hard pressed to prove that any of the visual aides added around the lower edge of conversion vans has any positive effect on lowering drag numbers. Particularly at the speeds that vans operate at. I would like to see the claims of any manufacture that says they will lower drag.

Gene