Fuel milage as per "Myth Busters"

Was watching the show Myth Busters the other night where they tested several senerios below.

1. Tail gate up
2. Tail gate down
3. Tail gate Net
4. Truck bed cover

What I can remember is that they got better milage with the tail gate up VS having it down.
The best milage came with one of those tail gate net things.

 

i seen that too, myth busters is pretty cool they get to do soem wild stuff on there dont they

 

i got about 20mpg in my truck with the tailgate up and no cover