Given that there are some ‘normal’ sized EVs that find 3 miles per kWh a good return, I’d say you’re doing great. My ZS gets between 3.5 and 5 in the summer, depending on how heavy my foot gets and 2.5 – 3.5 in the winter, so again, 3 is pretty decent seeing as you’re twice the size.
If you can avoid public charging, 5p per mile is expensive. At current fuel costs, I dread to think what the average dino fueled car costs per mile.