The petrol range will increase when you top the battery up, as the petrol guage shows the total range available with a full or empty battery.
As previously said, what I found with this and the previous Tucson, is the economy will start to improve after 1,000 miles.
Your journey isn’t adding up! If your outward journey was for simplicity 40 miles, you would have got, dependng on how fast you drove? around 35 miles say in electric, meaning you had 5 miles to your destination in Hybrid driving, arriving at your destination with zero electric miles!
Your return journey therefore, should have been in Hybrid mode!
However, you are saying, you acheived 40 miles electric going and 20 miles electric on the return journey, making a total of 60 electric miles? The best I have acheived was just under 42 miles coming home yesterday in slower than usual 50-60mph traffic.
Something isn’t right their buddy! My thoughts are (a) most likely scenario – In Auto mode, the car deemed it necessary, to do some of the outward journey in HEV as well as EV mode, probably on the motorway at “x” speeds (b) you accidently at some point knocked it into HEV mode, hence for one of these reasons the car held the battery level at times driving as a hybrid and the reason for your 20 mile EV range at the start of your return journey.
As long a the power meter stays in eco range or no further than about 25-30% into the power range, you should theoretically stay in EV mode. I can do about 83mph in electric as long as I don’t plant it to overtake.
When, we did my last calculation after Oscarmax kindly posted the sum, I arrived home according to the GOM with an average of 53mpg however after doing the calculation it was actually 56.6mpg. So I’m going to have a stab in the dark and say you acheived at least 80mpg for your trip 😁 I base this on the fact that Wales is mountanous and therefore hilly, which I will trade for your constant speed motorway journey 😂
What, I will say is, do as I did at the begining, which is to get a costing for each out of town journey/per mile. By that, I mean fill up tomorrow and do the costing for this journey and do the same when you go on holiday. By doing this you get an average of what each journey is likely to cost, otherwise you won’t have a clue of whats likely cost what, to start with. Then move on to costing a full tank per mile.
Finally before I fall asleep. If a gallon of petrol costs £6.22, you would need a car capable of 83.65mpg, for the equivulent cost of a PHEV, based on a range of 35 miles per charge. Well that was pointless wasn’t it 😂