It all depends on what you mean by good MPG, regular trailer, and how much space you want. Gas mileage is determined mostly by how much frontal area you are trying to push through the air, and how fast you are trying to push the air out of your way.
Most small molded fiberglass trailers are lower and narrower than mainstream travel trailer designs, thus have less frontal area, need less power to pull them. They are also built to be lightweight. But most people don't consider them to be regular trailers.
For example, the Scamp.Otherwise, hard-sided collapsible trailers, which tend to be the full eight-foot with, but collapse down to a 6 to 7 foot height, higher that a popup but not as high as the 9 to 12 feet of conventional TTs. The smallest of these are lightweight, but they do get heavier as your choice moves toward longer and more fully equipped.
TrailManor hard-side pop-ups.Next in line would be small lightly built TTs of more conventional design like the Lance travel trailer line, Jayco's SLX models, and Forest River's R-Pod. But these are all full size box, 80 sq ft or more frontal area.
