The article says highway mileage will improve but the primary advantage of a hydraulic hybrid is in stop and go driving. If the article is correct they could produce a vehicle with better fuel mileage in town than on the highway.
As to your question. If you drive your pickup 80 mph fuel economy isn’t something you need concern yourself with. ;^)
My ‘01 GMC Sierra 4WD gets about 18 mpg. It has 81,000 miles and has been trouble free.
My next truck MUST get better miles per gallon.