Comment by paulbgd

This does exist, the Maextro S800 is one example. Over 800 mi with the gas extender. For trucks there's the Ram 1500 Ramcharger, and Mahle makes a drop in attachment for EV truckers.

I think for most consumers though, if you want that range I wouldn't go EV. At the point where you're adding extra weight via engine + gasoline you're giving up range, and we've already figured out what the most efficient gas vs battery tradeoff is in hybrids. Like the Hybrid Camry with 600 mi of range is insane, if it had a bigger battery (with current tech) you'd just be losing range from the additional weight