PHEV Economy

I can't for the life of me understand all the discussion about PHEV mpg in posts, from motoring gurus and, including Mitsubishi compounding the problem by quoting it in marketing literature.
True PHEV economy can only be measured in terms of energy cost per mile (petrol and mains electric) and only then can it be compared to an ICE vehicle cost per mile. PHEV energy cost per mile is entirely dependent up one's journey profile and driving style. Mine is approx. 60% local mileage and 40% motorway and 9000 miles per year of leisurely but not dawdling driving style.
I measured costs over a period of three months of monitoring electric meter readings, recording petrol (BP Ultimate) costs and mileage covered.
Result is 9.0 pence per mile. compare this to an ICE vehicle of similar size, say Nissan X-Trail petrol, of 13.4 pence per mile. On my journey profile, that equates to a saving of £396 per annum.
Now you can start arguing the toss over cost of ownership!

Pickygit said:

I can't for the life of me understand all the discussion about PHEV mpg in posts, from motoring gurus and, including Mitsubishi compounding the problem by quoting it in marketing literature.
True PHEV economy can only be measured in terms of energy cost per mile (petrol and mains electric) and only then can it be compared to an ICE vehicle cost per mile. PHEV energy cost per mile is entirely dependent up one's journey profile and driving style. Mine is approx. 60% local mileage and 40% motorway and 9000 miles per year of leisurely but not dawdling driving style.
I measured costs over a period of three months of monitoring electric meter readings, recording petrol (BP Ultimate) costs and mileage covered.
Result is 9.0 pence per mile. compare this to an ICE vehicle of similar size, say Nissan X-Trail petrol, of 13.4 pence per mile. On my journey profile, that equates to a saving of £396 per annum.
Now you can start arguing the toss over cost of ownership!

Click to expand...

Fully agree - and your figures just reinforce my contention that the PHEV, with its current tax treatment, makes very little sense. In ten years, it will save you less than £4000 - significantly less than the price premium it will cost you over an X-Trail. When we bought it - as a company car for a company that we own, then it made some sense, but these days it would be very difficult to justify.

Mitsubishi have to quote the economy figure they do, using the method that is prescribed by the NEDC. They don't have any choice, it's the law. It would be good if the NEDC was upgrade to give more realistic figures for hybrids. Then again, it's possible for some drivers to exceed the NEDC figure if they use entirely or almost entirely EV miles.

Regarding the cost relative to a diesel.... The whole point for me was to NOT drive a smelly polluting diesel. Not everyone is obsessed with saving money regardless of the wider considerations.

Steve

Why compare with BP ultimate? Common fuel is standard unleaded.

For those who don't know, there are three MPG numbers:

The EV MPG number is obviously infinite. This is when driving on battery power only.
The quoted hybrid MPG number, which is 49 MPG (if I am not mistaken). This is without plugging in ever.
The quoted plug-in hybrid MPG he hybrid MPG number, which is 149 MPG (again if I am not mistaken). This is when using the car as 'intended'.

The last number assumes a trip during which you empty the battery, which gives you 32 miles, and then use petrol to get to the next charge station, which is another 16 miles away. ((32 miles * infinite MPG) + (16 miles * 49 MPG)) / 48 miles yields 149 MPG. This formula may seem odd, but you guys should have adopted l/100km. That makes more sense: ((52 km * 0.0 l/100km) + (25 km * 5.8 l/100km)) / 77 km yields 1.9 l/100km :mrgreen:

The 32 miles is per product specification (although very optimistic).
The 16 miles is per NEDC rules.

Bottom line: the bigger the battery, the better the plug-in hybrid MPG.

The economy will vary greatly on your usage profile. I use about 8000 miles per year, but around 3/4 of these are local journeys, less than 20 mile round trips, which in a newer PHEV with the EV button you can do completely on petrol.

But even on the profile I'm not saving enough to cover the extra cost. However I really like the driving style/power delivery in the PHEV vs say the diesel equivalent, and a diesel is really not ideal for lots of local journeys and I'm likely to end up with a big bill for en EPF.

Is it economically sensible? Probably not, but I've just ordered a new one anyway!

Not sure if the following will render, but I have been tracking since January the PHEV economy and have the following raw data:

Date ....... Miles Total .... Trip ..... Meter .. PV Reading .. Unit Cost ... Liters ... £/Ltr ... Petrol .... Electric ... Total ..... MPG ... Pence Per Mile ..... Fuel ...... Journey
14/01/2017 ... 20112 ..... 278.4 ... 0093.5 .................. £0.11364 ... 25.44 ... 1.219 ... £31.01 ... £10.66 ... £41.67 ... 48.7638 ... £0.149679569
22/01/2017 ... 20444 ..... 332.4 ... 0178.7 .................. £0.11364 ... 32.81 ... 1.219 ... £40.00 ... £09.65 ... £49.64 ... 45.1440 ... £0.149348454
11/02/2017 ... 20937 ..... 492.9 ... 0377.9 ... 8136.3 ..... £0.11364 ... 32.36 ... 1.279 ... £41.39 ... £22.64 ... £64.03 ... 67.8728 ... £0.129895573 .................. Town
18/02/2017 ... 21241 ..... 303.8 ... 0425.4 ... 8155.5 ..... £0.11364 ... 32.26 ... 1.209 ... £39.00 ... £05.40 ... £44.40 ... 41.9632 ... £0.146149572 ... BP Extra ... Motorway, Town
23/02/2017 ... 21482 ..... 241.8 ... 0475.6 ... 8165.3 ..... £0.11364 ... 23.76 ... 1.219 ... £29.00 ... £05.70 ... £34.70 ... 45.2905 ... £0.143526625 ... BP .......... Motorway, Town
04/03/2017 ... 21855 ..... 371.5 ... 0583.0 ... 8193.5 ..... £0.11364 ... 30.67 ... 1.239 ... £38.00 ... £12.20 ... £50.21 ... 53.9747 ... £0.135141497 ... Shell ....... Motorway, Town
04/03/2017 ... 22096 ..... 240.5 ... 0583.0 ... 8193.5 ..... £0.11364 ... 36.32 ... 1.239 ... £45.00 ... £00.00 ... £45.00 ... 29.5063 ... £0.187112183 ... Shell ....... Motorway only
18/03/2017 ... 22524 ..... 428.8 ... 0728.1 ... 8251.6 ..... £0.11364 ... 23.22 ... 1.249 ... £29.00 ... £16.49 ... £45.49 ... 82.2882 ... £0.106088955 ... Shell ....... Town
02/04/2017 ... 22966 ..... 441.4 ... 0857.6 ... 8338.3 ..... £0.11364 ... 31.18 ... 1.219 ... £38.01 ... £14.72 ... £52.72 ... 63.0814 ... £0.119449026 ... BP .......... Town
08/04/2017 ... 23259 ..... 292.9 ... 0900.4 ... 8368.0 ..... £0.11364 ... 34.78 ... 1.179 ... £41.01 ... £04.86 ... £45.87 ... 37.5262 ... £0.156604343 ... Shell ....... Motorway only
23/04/2017 ... 23693 ..... 434.2 ... 0990.4 ... 8469.6 ..... £0.11364 ... 35.03 ... 1.199 ... £42.00 ... £10.23 ... £52.23 ... 55.2325 ... £0.120286895 ... BP .......... Motorway, Town
01/05/2017 ... 24052 ..... 358.6 ... 1055.3 ... 8511.1 ..... £0.11364 ... 34.65 ... 1.299 ... £45.01 ... £07.38 ... £52.39 ... 46.1161 ... £0.146083620 ... BP .......... Motorway, Town
09/05/2017 ... 24329 ..... 277.2 ... 1120.8 ... 8543.7 ..... £0.11364 ... 19.69 ... 1.169 ... £23.02 ... £07.44 ... £30.46 ... 62.7325 ... £0.109888276 ... BP Extra ... Motorway, Town
26/05/2017 ... 24954 ..... 625.5 ... 1262.1 ... 8666.2 ..... £0.11364 ... 34.25 ... 1.139 ... £39.01 ... £16.06 ... £55.07 ... 81.3789 ... £0.088038500 ... BP .......... Motorway, Town
04/06/2017 ... 25229 ..... 275.8 ... 1306.0 ... 8719.4 ..... £0.11364 ... 24.19 ... 1.199 ... £29.00 ... £04.99 ... £33.99 ... 50.8047 ... £0.123250928 ... Tesco ...... Motorway, Town
23/06/2017 ... 25957 ..... 727.6 ... 1495.1 ... 8855.3 ..... £0.11364 ... 31.96 ... 1.189 ... £38.00 ... £21.49 ... £59.49 .. 101.4451 ... £0.081761633 ... Tesco ...... Motorway, Town
25/06/2017 ... 26283 ..... 326.0 ... 1514.5 ... 8870.4 ..... £0.11364 ... 34.25 ... 1.139 ... £39.01 ... £02.20 ... £41.22 ... 42.4133 ... £0.126427503 ... Tesco ...... Motorway only
22/07/2017 ... 26815 ..... 532.1 ... 1665.3 ... 9035.4 ..... £0.11364 ... 24.37 ... 1.149 ... £28.00 ... £17.14 ... £45.14 ... 97.2933 ... £0.084829998 ... BP .......... Motorway, Town
29/07/2017 ... 27126 ..... 310.4 ... 1711.2 ... 9071.3 ..... £0.11364 ... 28.00 ... 1.289 ... £36.09 ... £05.22 ... £41.31 ... 49.3979 ... £0.133080142 ... Tesco ...... Motorway, Town
24/08/2017 ... 27729 ..... 603.5 ... 1866.6 ... 9214.0 ..... £0.11364 ... 32.51 ... 1.169 ... £38.00 ... £17.66 ... £55.66 ... 82.7190 ... £0.092235039 ... BP Extra ... Town
02/09/2017 ... 28078 ..... 348.6 ... 1932.8 ... 9273.0 ..... £0.11364 ... 25.46 ... 1.179 ... £30.02 ... £07.52 ... £37.54 ... 61.0118 ... £0.107688778 ... BP .......... Motorway, Town
04/09/2017 ... 28299 ..... 221.1 ... 1949.5 ... 9275.6 ..... £0.11364 ... 30.11 ... 1.229 ... £37.01 ... £01.90 ... £38.90 ... 32.7207 ... £0.175951958 ... BP .......... Motorway only
17/09/2017 ... 28938 ..... 639.1 ... 2125.3 ... 9333.4 ..... £0.11364 ... 30.03 ... 1.199 ... £36.01 ... £19.98 ... £55.98 ... 94.8328 ... £0.087598000 ... Shell ....... Motorway, Town
21/09/2017 ... 29162 ..... 223.3 ... 2170.2 ... 9346.9 ..... £0.11364 ... 20.02 ... 1.199 ... £24.00 ... £05.10 ... £29.11 ... 49.7015 ... £0.130346691 ... BP .......... Motorway ....... Service and new front tyres
01/10/2017 ... 29708 ..... 546.9 ... 2300.0 ... 9389.1 ..... £0.12655 ... 35.86 ... 1.199 ... £43.00 ... £16.43 ... £59.42 ... 67.9583 ... £0.108653008 ... Shell ....... Motorway, Town
13/10/2017 ... 30283 ..... 574.1 ... 2466.0 ... 9427.9 ..... £0.12655 ... 31.28 ... 1.119 ... £35.00 ... £21.01 ... £56.01 ... 81.7836 ... £0.097560739 ... BP .......... Motorway, Town
22/10/2017 ... 30617 ..... 334.1 ... 2519.7 ... 9452.5 ..... £0.12655 ... 32.80 ... 1.189 ... £39.00 ... £06.80 ... £45.79 ... 45.3887 ... £0.137069545 ... Sainsbury's . Motorway, Town
01/11/2017 ... 31108 ..... 490.9 ... 2650.9 ... 9483.8 ..... £0.12655 ... 32.58 ... 1.289 ... £42.00 ... £16.60 ... £58.60 ... 67.1409 ... £0.119370503 ... BP .......... Motorway, Town

I haven't deducted the micro generation rebate but am tracking for info. only. We average about 12p per mile when you factor fuel and electric cost.

Anyone tracking similar data? I'd like to compare.

NB: Still confused when to use which mode for, so we ALWAY select the green EV button and crank the breaking regen up to B5 on every journey, plus cruize control on the motorway runs. Any advice would be appreciated.

Wow that is a lot of fill-ups. I have a similar spreadsheet for petrol, not recording electricity at all. My spreadsheet only has 5 rows so far, so not enough to draw any real conclusions.

I try to use my electric miles in town or traffic congestion. So if I'm going on a long journey, I will press Save as soon as I am out of the built up area, and save the battery for the other end. Of course if the journey is short I use the battery up. I don't have the EV button but presumably if you habitually press that at the start of your journeys then you use up all the electric miles at the beginning.

I think the best way to use the regeneration is to match the setting to the amount of retardation you need. I tweak it all the time. On a motorway with gentle fluctuations of speed it's probably best to not regen at all, but to coast in B0. If you need to lose more speed then set the regen to the lowest setting that would bring you to the correct speed in the right place. Round town B5 can be nice. Threading through a series of roundabouts B3 or B4 can avoid using the brakes. On a long gentle downslope B1 or B2 can keep the speed in check and get a bit of regen. But even if you always select B5 you can still achieve the effect of a lower B setting by feathering the accelerator jut the right amount, rather than lifting off completely.

Steve