dodge guy wrote:
Everyone saying that they have used one and got better mileage and you still don’t like the answer.
But not "everyone" is saying that. I know a couple of guys who added them...then a year or so later they got rid of them because it was more hassle mounting and demounting with no improved MPG to show for it.
As stated before, there is a huge amount of variability between RV configuarations and then claims with no attempt at consistent testing...if everyone got noticably better MPG, I'm sure you would see 90% of towing trucks with air deflectors...yet the exact opposite is true.
On the other hand near 100% of semis pulling standard box trailers use them. You can bet the trucking manufacturers and haul companies have tested and confirmed how to implement to get the maximum benefit but unlike RVs, it's a very standardized configuration, so easy to apply to the next truck they buy.
