Stupid is as stupid does

OUT: EVs. IN: EREVs. “What’s EREV mean? It stands for extended-range electric vehicle, and it’s distinct from the plug-in hybrids Hyundai and others more commonly offer. As the name implies, it’s an EV, with a decent-sized battery powering electric motors that in turn propel the car down the road. The whole range-extender part comes in the form of an internal-combustion engine whose sole purpose is to act as an onboard generator for the electric bits. Simply fill the tank with gas, and you can extend the vehicle’s effective range beyond a set radius surrounding an EV charger, with the engine kicking on to generate electricity when the battery’s initial charge is depleted. ….

So if I have this right, instead of one engine in a car we’ll now have two, one to keep the other running; aside from adding expense, weight and an extra motor to maintain, this is an improvement … how?