Maybe I can help ..........I have had my Mini PHEV for about 12 months now .........I am retired and a volunteer on the canals in England so my journeys are short , less than 10-20 miles I typically get 16-18 miles from battery alone . This has depended on ambient temperature for charges etc , so in Winter 16 miles in Summer 20 miles on battery alone . But of course heater , seat warmers , lights a/c will impact on distances achieved .
Also on a longer journey (these are in Imperial units not US gallons etc) my tank+ batteries will take me about 240 miles , but after 230 miles I have 100 miles left in the tank/batteries ..........this is because of the regeneration . So far I use need about 9 miles per Kw petrol consumption is 63 MPG (imperial) and regeneration (recuperation) is 12 miles per Kwatt.......this is real data from a user that wants to keep cost down and as green as I can be .........hope this helps .