[skyking]

Originally Posted by greengeeker

Thanks for amassing all the information together into an article - very helpful to have this all in one place.

I've put together a TDI Ranger and have been driving it for the last two years with the intentions of improving on the rock steady 39mpg (stock aero) with some aero mods. What I haven't seen (not necessarily directed at your article) is a list of priorities as far as aero is concerned. Which heavy hitters do you need to tackle first to make aero gains so that subsequent aero mods are actually beneficial. On a truck, which has the highest impact on aerodynamic drag? Is the airflow over the bed? Airflow under the truck? Yes, the answer is likely to be different for each truck but the order is going to be different for a truck than it is for a car.

Anyway, on my truck I've tried two things to improve the FE: 1) removed the 3.73 rearend and installed a 3.08 dropping cruising 5th gear rpm by 450rpm. 2) installed a hard tonneau cover on the bed

Neither of these showed any impact on my long term mileage.

I'm considering moving forward with some underbody mods (dam, belly pans) to see if this has a more significant impact.

(I don't have enough posts to include links or pictures so if you want to see info on my truck just google "tdi ranger build tdiclub")

Another TDI fan here, I have a couple of beetles.
Your ranger is a good candidate for an aeroshell. how you build it depends on your skills and time.
One method that I'd do for the fun of it is wood strips, like a cedar strip canoe.
Instead of removing the plywood formers, plan on cutting most of them away and leave a 2" bulkhead there. This does a couple of things. Now you can glue and fasten the strips to that for easier construction, use less formers, and it will be stronger. It also give you attachment points.
If you want a lift lid, cut it out and build a gutter down each side of the fixed part for the lid to rest on and to carry rain to the back.
4 oz fiberglass is invisible and will show the wood perfectly. 6 oz is not too bad either.
coupled with a few other mods it should net 10% MPG improvement. That is where my beetle is at, around 45 or so.