[ansgri]

Would be best to have a modular generator for an EV, that would allow slower but practical charging while on the go or at rest. This would be basically a series hybrid with modular generator, not popular due to lower efficiency AFAIU. Just explicitly design for lower performance when battery critically low and is charging on the go.

[prescriptivist]

These are called EREVs in China and are fairly popular. Ford has a patent for one in trucks but never built it. It makes a ton of sense. Use the generator to get extended range, but avoid all the moving parts of a driveline.

[to11mtm]

Stellantis almost built one, I think the Ramcharger?

A couple other companies tried EREVs but AFAIR one was suboptimal (Mazda had one but the motor was so small it was dangerous to use for uphill) and the other was in an expensive German thing.

Where it is challenging is that, AFAIK, a direct driveline (i.e. Honda's system) or close to (THS used by Toyota/Ford/Subaru/others), it is easier to hit a higher Gas-only MPG rating than with an EREV due to the conversion losses on each end.

And, If you compare a BYD Seal 5 DM-i to the Current Prius Prime, AFAIK if you compare euro WLTP numbers the Prime gets better MPG when it switches to gas, and has a competitive electric only range. The Seal 5 DM-I is a little bigger but close enough. The BYD certainly wins on 'price' however it is unclear how much of that is due to a truly simpler design versus labor/material input cost.