aerodynamics

would adding a peice of fiberglass or carbon fiber to the back of a truck to make it shaped like a fastback help give it a higher top speed if it's wind resistance limited as opposed to gear limited? If it does, at what speed would you notice a difference? I've heard that some aerodynamic stuff doesn't make a difference untill somewhere around 50mph, would it help at this speed or higher?

The reason i ask is because i was wondering if a truck would create a vacuum behind it because it's a pretty flat back and generally that creates a vacuum. I also heard that lowering your tailgate gives you better gas mileage, this makes sense to me because it would create wind resistance, am i right or not?

i've read that trucks cabs are generally designed for aerodynamics based on the tail gate up that creates a bubble so to speak behind the cab and directs airflow around it, i have a big pile of snow that seconds this because the snow is higher behind the cab than near the tail as to be expected. I don't watch it much or know much about it, but Nascar Trucks have flat covers over the bed don't they? I don't know about rules and such but I think they try to gain every second they can and would think they would make the cap you are talkin about if it was better.

i would think that this kind of cab is banned because it would make them too fast, they already ban pointed noses, spoilers, and a whole bunch of other aerodynamic stuff that it wouldn't surprize me if they banned this.

nah thats why they have restritor plates, the trucks have spoilers in the rear im talking Craftsman Trucks...nascar can always slow em down by taking away their airflow. I partly have no clue what I'm talkin about so don't mind me, just offering a theory...

Trying to make a silk purse out of a sows ear.
You trucker guys crack me up!

that was a "cute" comment, you think that sleek cars are the only thing on the road? don't flame because people have different taste...I also drive an S60 AWD so stick to the "silk purse" threads please.

It would create excessive lift in the rear, basically turning the truck into an airplane wing, it would have almost no traction at high speeds in the rear and at a certain point would accually lift off the road surface.

First off I am trying to remember what exactly the proffesor said about it in class two years ago, but leaving the tail gate down does not decrease aroedynamic drag. With the tail gate up, most of the air stays trapped for some time creating an eddy, or sirling pool of air, that the air coming off the top and sides of the cab flows over for the most part. much like the covered beds in craftsmen truck series.
As far as shaping it like a fastback, I am assuming at a downward slant from front to rear, i am not sure.

that was a "cute" comment, you think that sleek cars are the only thing on the road? don't flame because people have different taste...I also drive an S60 AWD so stick to the "silk purse" threads please.
If I recall correctly, an S60 AWD is an ugly vehicle as well, so at least you are consistent in your lack of good taste.
You're correct 'tho, I shouldn't lower myself by posting in Sows Ears threads.
I should only make posts in silk threads ;).
Enjoy your crappy gas mileage.

have a good day, try to look up the definition of maturity on your way out. form over function and the S60 in the wifes car so have a good day...