30 mpg Ranger Supercab
 

In June I bought a 2011 Ranger XLT Supercab with the 2.3 4 cylinder and 5 speed manual. It's 2wd. At 60 it gets 30 mpg. At 70 it gets 27. I drive mixed in town and rural delivering pizza getting 20mpg, so I'm not often at highway speed. I'm thinking of just adding a flat bedcover with treated plywood. It would be nice to keep the snow out of my trucks bed. Would I see an increase with the bedcover?

bedcover
 

here is the drag table for GM's bedcover which includes data for a full cover.
The C-10 pickup they tested had around Cd 0.535.You can see the change the cover provided.
On a percentage basis,the best you could probably see is this percentage change.
Your Ranger is much 'cleaner' than the C-10,and the gain from the bedcover might be less.
http://i1271.photobucket.com/albums/...titled7_18.jpg

Sorry I'm confused looking at that attachment. I'd make a full length bedcover.

The drawing shows that a full length cover is worse aerodynamically than one that covers only the last 50%.

I'd rather keep the snow out it will be a full length cover.

attachment
 

At the bottom right of the table,you'll see data for the 100% length (full) cover.
The drag coefficient change around 0.032
Starting at Cd 0.535,the full cover got GM to around Cd 0.503.
That's a 5.9% drag reduction,and good for about 3% better mpg.
That's as much as you could hope for basically.

3%= then maybe 1 mpg on the highway and almost nothing in mixed driving. At least I'd keep the snow out. If I had more $$ I'd make an aero curved sloping back topper out of lexan or similar.