It is very interesting topic to discuss about the Subaru’s first hybrid Forester fuel consumption or MPG if you will. Looking at the official WLTP numbers, it seems that Subaru managed to improve fuel efficiency little. According to Subaru, new e-Boxer Forester can save in fuel consumption up to 11% compared to non-hybrid variant.
|Subaru Forester e-Boxer||WLTP (lit./100km)|
Combined WLTP fuel consumption is 8,1 litres per 100 km. Bear in mind that this is done in certain temperature and official WLTP cycle just little over 20 kilometers. So driving in different temperatures, it is expected to have different results. Of course, colder it is, worse the fuel economy will be. Tank capacity is 48 liters. Depending of your driving style and conditions, cruising range is somewhat 500 km.
Winter vs summer fuel consumption
I am using 95E10 fuel at winter and summer. That fuel type contains maximum 10% of ethanol. Some believes that higher octane gasoline is better. Either it would save some fuel or give extra power for your car. I do not believe that. I’ll just use what is recommended by Subaru.
Tires have also impact to the consumption. During winter I am using Continental Viking Contact 7 (non studded) tires, 17″ wheel. Summer tires are those which came with car, i.e. Bridgestone 18″.
Outside temperature has also impact to the fuel consumption. Last winter was almost like a “long autumn”, it was not a proper winter at all. Temperatures were above zero Celsius. So unfortunately I do not have data available how e.g. -15 Celsius would affect. Hopefully we can see that next winter. Traditional colder weather affects to the consumption like camel drinks water in Sahara desert. Only comparable data I have available for now is that I did “hypermiling” tests in zero degrees vs 20 degrees. Results was 5.7 litres vs 4.9 litres per 100 kilometres.
Speed kills fuel economy
Above I state that outside temperature has a impact to the fuel economy. That is true but then also speed affects to the fuel economy greatly. Particularly true it is with taller cars such as Forester. 4th generation Forester (SJ) has drag coefficient of .37 cd, 5th generation Forester (SK) should be close to that too as the exterior shape is pretty much similar than it used to be. In comparison, drag coefficient champion, Toyota Prius has .24 cd.
Below table is not measured by any means, rather these are results of my experiences from summer period. Please note terrain forms affects, wind direction affects. So these observations are not that accurate but gives an idea what the consumption is in different speeds.
|Speed (km/h)||fuel consumption (litres / 100 km)|
3rd main factor which affects to the fuel consumption is distance you drive. In short distance driving, engine never gets to the optimal operating temperature and hence relatively average consumption is higher.
Short distance driving might be also harmful your car. E.g. GPF filter needs regenerating procedure more often. This filter is installed only in the EU spec e-Boxer models. US models are free of this device. Lucky you!
Subaru Forester e-Boxer monthly fuel consumption statistics
Table below is presenting real world consumption figures of my driving. See journal below to learn more details from each month.
|Month||distance driven (km)||liters / 100 km||US MPG||UK MPG||Avg. outside temp.||Tyres|
|January||1478||8.2||28.7||34.5||+3C / 37.5F||winter|
|February||1843||8.3||28.3||34||+1.4C / 34.5F||winter|
|March||1240||8.2||28.7||34.6||+2.4C / 35.6F||winter / summer|
|April||590||8.2||28.7||34.5||+5.1C / 41F||summer|
|May||848||7.6||31||37||+9.6C / 49.3F||summer|
|June||775||7.9||29.8||35.8||+17.9C / 64.22F||summer|
|July||2326||7.4||31.8||38.2||16.7C / 60.8 F||summer|
|August||584||8.4||28||33.6||17.1C / 62.8F||summer|
|September||596||8.5||27.4||32.8||13.8C / 56.8F||summer|
|October||850||8.5||27.4||32.8||9.3C / 48.7F||summer|
Journal of the fuel consumption (2020)
Before the Covid-19 pandemic I used to drive to my office daily. 8km distance one way. So very short trips and cold starts for the engine. That did not do good for the fuel consumption. Now during pandemic I don’t need to drive to office any more but I still have some short distance driving, e.g. to grocery store. But then also some long distance driving during my free time.
Below I have gathered monthly insight of the fuel consumption for those who are interested what type of conditions each month had and what type of driving it included.
This was only half month what comes to the driving. I received car mid January, brought it to home from the dealership. First 500 km was long distance driving. Speed limits from 60 to 100km/h. During that trip fuel consumption was 7.1 liters per 100 km. Outside temperature was few degrees over 0 Celsius by then. Next I had some short distance driving. To work, back to home, to the grocery shop, etc.. That increased consumption to 8.4 liters per 100 km. Few longer work trips via a highway. Some city driving with lot’s of traffic lights. Total 1478 km distance driven. Average temperature for January +3 Celsius (Helsinki) and average consumption was 8.2 liters per 100km.
February started with a bit colder temperatures. That was shown as slightly increased fuel consumption. Nothing major. On this month I decided to do a “hypermiling test“. My goal was to beat official WLTP figures. Test went quite fine indeed, given that it was conducted during winter time. Result for that 60km test was 5.7 liters per 100km.
During this month GPF orange warning light lit also. Luckily I managed to get rid of that driving in certain conditions. Please check separate post of it.
Otherwise February included some driving through storm, some longer business trips and then short distance driving between home and office. Roughly 400km more than in previous month. From weather wise this month was bit colder than January, average of 1.4C. We saw even a glance of snow.
March started with some business related trips, which generated kilometers to the odometer. However from mid month we got advise from the employer to stay home and quickly after also from the government similar advises due to the domestic (and global) virus issue. So in March it seems that there is less distance driven and in general shorter distance driving, which increases fuel consumption.
Summer tires was changed on 24th of March. So that is also interesting to see how those will affect to the consumption. Winter tires are inch smaller than the original 18″ summer wheels.
I would assume that upcoming summer months will have still lower consumption figures. Bigger tires will increase consumption but warmer weather does have a greater impact. Thus lower fuel consumption is expected.
Final figures for March are 8.2 liters average consumption and 1239.7 km driven.
April seems to be bit odd month. At least first half of it. Currently average consumption is 8.4 liters per 100km. Which is higher than expected. Days have been warmer and that should have positive impact. Although work related driving is nearly zero due to the global pandemic. There has been less free time related driving too during this month.
April update: Less than 600 kilometres driven at April. Significant drop is because I have been working fully from home. So basically that is only some hobbies related driving or just going to grocery store.
Hopefully weather gets warmer during May and then also fuel consumption should drop too. I expect well below 8 litres per 100 km numbers. Let’s see!
I was right that outside temperature has a major impact to the fuel consumption. Beginning of this month was bit colder but on the otherhand latter part of the month was warmer. Specially these last days before heading towards June.
I also made a “hypermiling” test, similar test than I did during winter. Just to see what kind of impact weather does have. I recommend you to check at least summer test. Interesting results I would say!
So the average consumption for May was 7,6 litres per 100 km and total distance driven 848 km.
This month result was really unexpected for me. I though final results would be closer to seven litres per 100 km but it was actually 7,9 litres per 100 km. Weather has been extremely nice so outside temperature is favoring fuel efficient driving. It seems that for certain point temperature has a positive effect but the most biggest factors are speed and then distance.
This month distance driven is 775 km. Mostly short trips to get some supplies for the newborn baby and some food from grocery stores. That might actually explain “bad” fuel economy. There was some longer trips too but certainly that many as in previous months.
Record so far in monthly driving. In both distance driven and in fuel consumption. This month figures underpins that it is possible to get decent fuel economy when driving more long distance driving.
Half of the July’s driving was pleasure driving to relatives and other half very similar driving that I have been doing through out the year already.
If July was new record of monthly distance driven, so it was also in August. This time opposite. This was the shortest distance driven in one month. Only 548 kilometres. And mostly short trips. I also expected that GPF light would lit on once again but luckily that did not happen. Short trips also is immediately shown on the fuel consumption figures. For this month it was 8,4 litres per 100 km.
Global pandemic situation keeps mileage figures still low. In terms of driving, September was pretty much alike with August. However during this month average consumption was the highest with 8,5 liters per 100 kilometer. This was somewhat surprising as outside temperatures were relatively high through month. E.g. at April it was much colder but still little lower consumption.
At October I returned to my “new normal” driving distances by driving 850 km during this month. Mostly normal trips here and there (grocery stores) but we had also one hotel vacation in city of Hämeenlinna. Weather did not favor our visit but Subaru did not complain any of the gross winds. I guess this longer trip also was good for the GPF filter, although I have not yet learned to “feel” it when regeneration happens in normal operation.
From the fuel economy point of view, last two months has been most fuel sipping months by 8,5 liter average consumption. Reason for that is that short trips really increases the consumption. One longer trip does not “save” the fuel economy.