[sheepdog 44]

Also, a typical belt CVT takes about a 3-5% efficiency hit compared to a manual transmission. On top of that, the 1:1 gear ratio of a manual transmission is the most efficient than any other gear ratio at around 98% efficient (going from memory).

Remember where talking range extended EV's, not range extended Serial and Parallel hybrids (Chevy Volt / Plugin Prius). A pusher or a genset is something that you ideally would rarely use on an EV, so what costs the least is likely the best option.

A genset is cheapest and far lighter cause it excludes drive components, and added rolling resistance. It also has the ability to be removable. A genset that cannot provide 100% of the power needed at all times is a better option. Like the 600cc iBMW range extender that doubles the 100mile EV range to 200miles before it needs to be plugged in. The smaller your engine, the cheaper, the lighter, the easier to make removable from the EV. Otherwise you have a heavy Volt that always needs to carry the dead weight. If you had to build a business model on a pusher trailer or a carry on/ towable generator, The generator would win hands down.

Another point is that the pusher needs to be scaled large enough for peak horsepower (for trailer and vehicle), unlike a smaller genset which only needs to provide average power over a period of time. And with traffic included, that average can be lower still. Generally an engine that must provide peak power has a larger displacement, and thus is less efficient at a low power cruise.

Now you can argue that the Plugin Prius model is the most efficient system of using gasoline to move a car. And i would agree. But the Plugin Prius is not an EV, because it can run only on gasoline after 20 miles and potentially all the time if the user never charges. At that point it's just an efficient hybrid that burns gas, which defeats the purpose of having a clean emission free battery Electric vehicle in the first place. Which begs the point that engine to wheels is incompatible with EV's for many of the above stated reasons despite it's efficiency. Adding a pusher or genset to a 100% EV introduces a whole host of added compromises, which the genset mitigates for the limited intended use.

If the Plugin Prius (pusher) model is used correctly, it is the most efficient use of battery and gas resources. Having both a full EV range and a prius drive, would result in an expensive and heavy, and thus very inefficient version of the Volt. Which makes the smaller scale Prius pusher model almost an argument against the colossal waste that is the 100 mile range battery!