[ShadeTreeMech]

Bit of a newbie here, so excuse any newbie comments.

My '97 Mercury Villager would seem to have the perfect recipe for an economical car; it's decently streamlined, has a smaller v-6 with overdrive made by Nissan, and it is more compact than most vans. But it weighs in at nearly 2 tons (between 3800-4000) and despite using hypermiling techniques, we can barely get past 22 mpg in mixed driving.

It has a drag coefficient of .35, which doesn't seem terrifically terrible, but i suspect can be improved on. My first order of business is a belly pan, I think, but I'm having to argue with my wife about anything that can be seen. I've convinced her that a partial kammack wouldn't be too bad--Toyota's Prius has one, as do a lot of newer cars. But I'm not convinced that a part kammack will work unless it becomes a bit large.

While looking at the Prius, I noticed what looks like an air dam in the rear. Suppose it's like a part kammack for the under car air flow? Playing with the airflow video tool showed that a part kammack on top and bottom would seem to help some, but my guess would be they would have to stick out about 2 foot from the rear of the van. Don't know if the wife would appreciate that much. I might get away with it if I make the bottom kammack sturdy enough to strap a cooler to.

Something else I confirmed with the airflow video; a minivan is quite a bit more efficient going in reverse than going forward. In reverse, the hood would act as a kammack, and the video shows the airflow being much smoother. Too bad that mod was so difficult to do.......

thoughts?