I find maufacturers have gone lazy and use one tyre pressure across the board regardless of tyre size or differences in vehicle weight across the same models. It never use to be like that! In Hyundai Tucson terms this translates to tyre sizes 215/65/17, 235/55/18 & 235/50/19 all having the same tyre pressure of 35psi across various tyres aizes with different volumes. The other difference is there is nearly 400kg weight difference between the standard ICE and PHEV.
The Michelin Primarcy 4 tyre has a maximum inflation rate of 50psi, so there’s plenty of room for expansion when the tyres get warm at 38psi. Michelin also recommends a tyre pressure of 2.4 bar for highway use (39.8psi), so the general concensous is to run them at 38psi.
What that translates to in economy wise I don’t know but, Ive run mine at 38 since having it and I’m generally happy with those setting across the board.