I think the weight fo batteries makes massive difference. Perhaps you can why a plain ICE can do about the same mph as the identical one that is a hybrid.
Not quite same, but our Jeep was a 3ltr and weighed over 2200kgs. Our SIL has a 2022 Honda CRV. Our 2018 Jeep gave us about 30mpg yet the Honda was lucky to achieve 38mpg and it is a lot lighter and more modern.. Our current car is about 38mpg.
The Honda and the Lexus are hauling around a great big heavy dirty batteries and the mpg is penalised. If they did not have the battery I suspect that mpg will be about the same or maybe better. The reason why they currently do 38mpg is because the battery kicks in giving inflated readings for mpg. Hence my other thread.
I was referring to the weight of the car regarding NCAP, which was the issue you raised with the Polestar being bad for pedestrians. As you say, there was thread drift from weight with regards to safety, to speed with regards to safety, and then on to batteries for economy.
On the weight vs safety, we can see that there is little or no correlation in the eyes of NCAP.
We can also see there is no correlation between weight and drive train when examining the wide spectrum of vehicles available, it's more related to body shape and absolute size.
On the subject of economy:
Small hybrid batteries are only useful in low speed start stop city traffic. Their entire point is to capture unwanted kinetic energy when slowing down, and allow it to be reused to accelerate again. At constant speed over long distances, hybrid engines have almost no benefit to non-hybrid, and as you say, can be less efficient if the benefit of start - stop is lost due to loss of economy based on extra weight via rolling resistance.
However, what can be seen is that electric drive trains (the electric motor and battery) are dramatically more efficient that combustion drive trains. Adding a larger battery and external charging source (PHEV) allows the majority of the journey to be covered in electric mode, and the result is the perceived economy goes up markedly to 80mpg or maybe over 100mpg.
The logical extent of this is to rely purely on the battery for journeys, and remove the combustion element of the car, resulting in a BEV, the most efficient solution we have available today, returning efficiency equivalents of in excess of 150mpg.