It possibly could improve your gas mileage. With it on you are more aerodynamic thus making the car not have as much drag making it easier. While having it off makes the wind catch a little more onto the car, but these are myths I suppose.
No, not to any degree you will notice.
It would all depend on the gas mileage for the truck and the price of gas.
If you are referring to E85, from my experience using E85 actually lowers the fuel economy.
Using a vent mesh cover in a room can improve air circulation by allowing air to flow freely while keeping out debris and pests. This can help maintain a comfortable temperature, reduce humidity, and improve air quality.
Using a glass cover for a fireplace can improve safety by preventing sparks from escaping, increase energy efficiency by reducing heat loss, and enhance the aesthetic appeal of the fireplace.
This depends on whether or not you are using a bed cover. If you are using a bed cover, you can greatly increase the storage capacity of a vehicle. Find a truck's bed size to determine which has the largest bed, and go from there.
Using an attic door insulation cover can help improve energy efficiency in your home by preventing heat loss in the winter and heat gain in the summer. This can lead to lower energy bills and a more comfortable living environment.
You can optimize your vehicle's performance and achieve better gas mileage by using a performance chip. These chips can adjust the engine's settings to improve fuel efficiency and overall performance.
Using an exterior window sill cover can provide protection from weather damage, reduce maintenance needs, and improve the overall look of your windows.
Things to consider when choosing a rental truck depends on how long you will be using it, and what you are wanting it for. If you are wanting it to move from one place to another then you will want to consider the size of the truck and the MPG that you will get. If you are just renting a truck such as a pick up for a short haul or pleasure than the only thing I can think of is the gas mileage.
My car has SUPER great mileage! It has the best mileage ever!
A bike brake cover can protect your brakes from dirt, debris, and moisture, which can help extend the lifespan of your brakes and improve their performance.