Anecdotally, some brands are better than others. I test drove a Kia hybrid where the gas engine was pathetically underpowered and it ran constantly. Even when the battery was full it was still burning gas.

I think Toyota might be the only company with a good PHEV drive-train. A Prius or Rav4 PHEV can do highway speeds on battery. And they have a heat pump so the gas engine doesn't kick in unless it gets very cold.

Another factor is home charging availability. The Canadian government gives a rebate for PHEV vehicles, but they took away the subsidy to install L2 chargers. It's very attractive right now to buy a PHEV and never charge it just to get the purchase rebate.