Anybody with gauges (this thread) have some data to contribute that is better than seat of pants method?.

 

Same type of person that will roast someone for not using the search function. Can't have it both ways.

 

Trucks are engineered to be fuel efficient with no cover on their bed. Adding a cover does not improve MPG, it does only make the bed a trunk... safer and better.

Ever wonder why your tailgate is thicker in the middle? It's like a triangle. Aerodynamics.

 

Believe what you want but in the a Ford engineer clearly states at ~1:30 "There is one element that a customer can add to the truck to make it more efficient and that is a tonneau cover. Tonneau covers traditionally, in the tunnel, at least based on our testing here at Ford Motor Company with our truck. Tonneau covers are more efficient. It keeps the air from gathering in the back of the cargo box."


I guess I am assuming more efficient means improved MPG...


If you have proof showing otherwise, please post it!


A lot of people think their opinion is fact.

 

Never said my opinion was a fact, but I did say there were some real life condition tests done which showed no improvement or even a decrease in MPG. I'm guessing it's different from brand to brand as aerodynamics are not the same from models to models.

Quote :
Based on our testing here at Ford Motor Company with our trucks, tunnel covers are more efficient.

And their testing was based on what type tonneau cover and in which conditions? The 1000$ one they try to sell you at the dealership, or the 200-300$ Tonneau that most of us end up buying because it's ridiculous to pay that much for a piece of plastic?

Shooting white smoke at a truck that's inert is certainly a good indicator, but it's not a conclusive test.

 

It would stand to reason that they use the one they sell, which is a hard folding cover that sits flush with the bed rails. Pure speculation.

It is also mentioned that it's really the last 6 inches of the tonneau cover that does everything. It gives the air something to land on that's wider than the top edge of the tailgate.

Other comments suggest that the additional weight of the cover offsets the gain. But one would need to examine the difference of the engine load by adding 80lbs of weight, and the difference of the engine load by 4-5% greater aerodynamic efficiency. I'd put money on the engine load changing by something like 0.05% compared to the 0.5% -1.38% (speed dependent). Also, the additional 80lbs should have the greatest impact on initial acceleration from a stop, rather than maintaining speed. And the aerodynamic efficiency has nearly no impact on initial acceleration from a stop, and the most impact over 65mph.

It's fun to think about but takes very controlled testing to indisputably determine. Like a rolling dyno and a wind tunnel.

 

I would think its very difficult to tell in real life conditions whether or not a tonneau cover effects the mpg's of the truck. Too many variables... how hard was the truck driven when you(or whomever) measured top on/top off. Which roads, same roads? same exact traffic? same acceleration/deceleration each time? same traffic? same weather/wind/temp/road conditions?

The white smoke is fairly conclusive of what the cover would do to the aerodynamics of the truck, its physics and can be measured pretty well inside these wind tunnels. Yes, brand to brand could be different results...

I can drive my truck exactly 200 miles around town twice.. and measure gas mileage by hand. I can get 2 very different readings depending upon a large number of variables, including the ones I listed above. Real world tests can be convoluted at best to decipher.

 

The statements the Ford engineer made in the video are probably intentionally vague. How much more efficient????.....probably not much and probably only at certain speeds. What was the air speed in the demonstration? Cab and bed configuration probably also contribute to any efficiency difference. So a single cab long bed driven at low speeds could be very, very different than a 5.5 screw driven at high speeds. I'd certainly be willing to bet the conditions in that video are optimized for the demonstration.

 

And the longer the bed the more a cover is useful.

 

If you want proof, look at how clean the interior of your bed is next time you're driving around in mucky weather with dirty mist everywhere. The entire truck will be dirty, but the inside of the bed, rear window, and tail lights will be clean. That's the aerodynamics preventing turbulence and shows that the air flows over these areas since the dirty mist doesn't hit it.