I thought we were comparing to the diesel though, which does indeed burn more efficiently than an equivalent gas engine, I thought largely due to the much higher compression.We all know that the way an engine works is to burn the latent energy of fuel, combined with the correct ratio of air (14.7:1 for "stoich"). So if you need to produce X amount of horsepower to pull a load, you need to burn a certain amount of fuel and air, no matter whether it is a forced-induction Ecoboost engine or a normally-aspirated Coyote. Of course, certain engines are more efficient than others. But generally, a smaller engine operating further up its load curve operates more efficiently than a larger engine that is loping. So a smaller displacement Ecoboost should in theory be more efficient than a larger displacement V8.
Extra weight compared to normal EB. But the EB is terrible too with respect to MPG under heavy towing conditions, far inferior to an equivalent trailer tow using a Superduty diesel. the EB (and PB, which is just an EB plus battery/electric motor) is optimized to get great mileage when NOT using the turbos at all, which is how Ford gets to both claim great MPG and best-in-class towing and horsepower/torque. But the minute you use the later, you are dumping fuel with two turbos to create the torque, and the MPG benefits go right out the window. The theory here is great because even for people who tow, that is generally a secondary use, and most people drive their trucks empty most of the time. However, if towing is a primary use, buying an engine that is designed for efficiency WHILE providing torque (eg diesel) is a better way to go. I was required to jettison the Superduty diesel due to an HOA rule, tried to substitute it with a PB, which get the pulling job done, but at significantly reduced efficiency despite being a lighter truck.Why would the Powerboost towing MPG be any worse than the Ecoboost? It is an Ecoboost on the highway with a motor assist, which should make the economy slightly better.