While I don’t do it in the XC40 if I get a Phev again I’m more inclined to keep better track of my charging costs and rather than an mpg do a cost analysis as that’s a bit more relevant as while I only get 22 ish miles of electric often it’s charged at a rate much lower than 10p/kWh.
Each 32 mile day is saving me approx £2 based on 50mpg in previous car, and 45mpg in Volvo and 8p kWh
i wish id been more disciplined in recording though 🙁