> but plugins get closer to the less efficient alternative (regular hybrid) the more you use them.

As long as most of your drive cycle fits within the EV range of the plugin hybrid, they are cheaper to operate than a regular hybrid. The crossover point depends on the drive cycle and the cost of electricity vs gasoline.

I had a plug-in hybrid SUV that got 2.2miles/kWh in EV mode, which covered 75% of the miles I drove. The net savings were significant vs an equivalent plain hybrid SUV in my area, which would get basically the same gasoline miles/gal.

Using a plug-in hybrid as an EV can and will wear out the drive battery over the lifetime of the car. It doesn't even matter if you don't intend to keep the car for very long as a rational market will price this in. The cost ($10k or more) goes a long way at the pump.

But the problem is that means you drove a minuscule amount so if you’d bought a hybrid you would have still used very little gas and your car would have been much cheaper. Generously, the full range of a plugin hybrid is equivalent to about a gallon of gas.