In 2014, we made a very long road trip in the Vanagon (ALH engine with Malone Stage 1 Tune) pulling a popup camper. The engine averaged 26.544 mpg (GPS and Odometer verified). Burned 409.948 gallons over 10,881.9 miles.
In 2016, we made almost the exact same road trip pulling the camper with two additional adults and their luggage and stuff on board. The engine averaged 26.779 MPGs. Burned 443.213 gallons over 11,869 miles.
The only thing different with the engine was that I installed a larger exhaust system from the Turbo out and installed a new clutch. I made the exhaust change due to necessity opposed to seeking performance improvement.
Below, is the new exhaust which is larger and progressively larger from one section to the next all the way out. The previous exhaust was a cobbled mess that continued to be a nightmare in reference to supporting issues, breaking, etc.