I've seen videos of that car... don't they only have like 40 miles of range, and the range extender only holds like 5 gallons of fuel?

In an interesting turn of events there is a pack upgrade for the i3 that gives it more range than it started with!

https://mtgbattery.com/

This is the kind of hacking / upgrades I’d love to see. All in cost was about $6k when I last checked probably a little more now. You get a pack teardown, and new CATL cells. Range goes to 400km~.