Mpg "equivalent" on a plug-in hybrid - why so difficult?
Discussion
3 weeks into owning my first PHEV, a 2021 XC40 T5
Very happy with the car, and I can do most of my driving in Pure electric mode, at less than 4p a mile. The range display tallies pretty close to the actual mileage driven, and the smart plug/granny charger combo tells me that charging losses are averaging around 16%. All pretty straightforward - as long as I'm doing a short journey just using the battery.
Today I did a 46 mile round trip, with 5 stops. Obviously too far for just the battery (27 mile range), so I used pure electric mode for the low speed parts, and hybrid for the faster parts.
At the end, the car told me I'd averaged 66mpg, and had 5 miles of battery range left. The app "driving journal" breaks it down into 6 individual trips, and shows mileage, kwh used, kwh regenerated, and a rough guess of petrol used for each leg.
To accurately work out a cost for the trip, or an "mpg equivalent", I need to add the trip mpg and the kwh taken to recharge overnight, and do some maths. Not too bad for a single day, but would get messy over a full tank of fuel, which might last a couple of months.
Very easy on an ICE car, just reset the trip computer each time the tank is brimmed, 30 seconds with a calculator to work out the true mpg, and compare with what the car thinks the average mpg was. Do that a few times, get an average "correction factor", and then I can just apply that to what the car says - for example, if car says I got 50mpg, and I know it's 5% optimistic, I actually got 47.5mpg. Job done.
On today's example, it will probably work out at the equivalent of around 55mpg, but I won't know for sure until tomorrow when the car has been recharged.
The whole efficency thing with plug-ins is a mess. Official figures are pure fantasy, and I can see why now.
Maybe I should just not "worry" about it, but it's hard to change what I've done for 45 years in ICE cars.
Very happy with the car, and I can do most of my driving in Pure electric mode, at less than 4p a mile. The range display tallies pretty close to the actual mileage driven, and the smart plug/granny charger combo tells me that charging losses are averaging around 16%. All pretty straightforward - as long as I'm doing a short journey just using the battery.
Today I did a 46 mile round trip, with 5 stops. Obviously too far for just the battery (27 mile range), so I used pure electric mode for the low speed parts, and hybrid for the faster parts.
At the end, the car told me I'd averaged 66mpg, and had 5 miles of battery range left. The app "driving journal" breaks it down into 6 individual trips, and shows mileage, kwh used, kwh regenerated, and a rough guess of petrol used for each leg.
To accurately work out a cost for the trip, or an "mpg equivalent", I need to add the trip mpg and the kwh taken to recharge overnight, and do some maths. Not too bad for a single day, but would get messy over a full tank of fuel, which might last a couple of months.
Very easy on an ICE car, just reset the trip computer each time the tank is brimmed, 30 seconds with a calculator to work out the true mpg, and compare with what the car thinks the average mpg was. Do that a few times, get an average "correction factor", and then I can just apply that to what the car says - for example, if car says I got 50mpg, and I know it's 5% optimistic, I actually got 47.5mpg. Job done.
On today's example, it will probably work out at the equivalent of around 55mpg, but I won't know for sure until tomorrow when the car has been recharged.
The whole efficency thing with plug-ins is a mess. Official figures are pure fantasy, and I can see why now.
Maybe I should just not "worry" about it, but it's hard to change what I've done for 45 years in ICE cars.
I feel your pain. I had a Vauxhall Ampera for four years from new a few years ago and really enjoyed. However the MPG calculation was very basic. Essentially my 'lifetime MPG' when I handed it back was 175mpg, but that doesn't take into account how much I spent charging.
Still, the 50 mile range was sufficient for the vast majority of my journeys.
Still, the 50 mile range was sufficient for the vast majority of my journeys.
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