Composites companies, such as TPI, are reported to have been hired by the US military to find ways to save weight on vehicles. The objective is to compensate for armor and weapons, but the same technology will be excellent for fuel efficiency if used in the civilian market:

The cab was designed for the U.S. Army’s tactical wheeled vehicle fleet and addresses serious vehicle issues by being lighter in weight, highly durable, and strong enough to carry the heaviest of armor and mine blast protection.

TPI’s lightweight, all-composite cab allows soldiers to carry more protective armor, ammunition, and equipment because it weighs hundreds of pounds less than cabs constructed with conventional materials. For example, TPI’s cab would allow the accommodation of 400 more pounds of weight than a comparable integrated A-kit aluminum based design.

That is a lot of weight savings. Efficiency is a better real-world security value than big or heavy.