Tuesday, July 17, 2018

Chevy Volt 2015 gas consumption statistics - an Eastern Canada case study

2018-07-17 Initially posted
2019-06-02 Last updated

I am a climate scientist, not a car specialist.

In February 2015, after giving a scientific seminar on global warming, I asked myself what little step I could personally take to reduce my carbon footprint.

This started a month-long process of diligently doing my homework in terms of
  1. Thinking what my needs were with respect to my daily commute to work and occasional longer trips for family visits or vacation.
  2. Taking into account the reduction in electric range due to the very cold winters of eastern Québec, Canada.  See my post on Canadian winter temperatures and EVs (written in French).
  3.  Looking at all the battery electric vehicles and plug-in hybrids that were then available for sale in Québec and that I could afford (this did not include the Tesla model S...).
On March 27, 2015, I ended up purchasing a Chevy Volt (first generation, model year 2015), with the following specifications:
  • Battery: 17.1 kWh
  • Electric range: 61 km
  • Extended range (gasoline): 600 km
  • Combined city/highway gas consumption: 6.4 L/100 km
Well, you know, specs are just that, specifications.

From Day 1, I decided that at each gas filling, I would carefully note both the number of litres of gasoline purchased and the car's odometer reading.

On March 27, 2019, exactly four complete years after the car's purchase, I report my 1st generation Chevy Volt's gas consumption statistics for others to look at.

Below is a graphical summary of my 2015 Chevy Volt's gas consumption statistics over 4 complete annual cycles.

Over these four FULL years, the average gas consumption was 2.31 litres per 100 km (2.3 L/100 km). For comparison, the car I previously owned (Honda Fit 2009) had a combined city/highway/summer/winter gas consumption of 6.5 L/100 km.

Mission accomplished: by purchasing a plug-in hybrid electric vehicle (PHEV), I actually reduced my gasoline consumption by a whooping 65%! 😊

Interpretation of graphic
  • the horizontal red bars represents the seasonal median (50th percentile) gas consumption rates, so that 50% of the time, the gas consumption rate was higher than the red bar, and it was lower 50% of the time for each of the four seasons.
  • The lower blue horizontal bars represents the 25th percentiles
  • The upper blue horizontal bars represents the 75th percentiles
  • The small red dots represent individual gas fill-ups that are either below the 25th percentile or above the 75th percentile.
The lowest gas consumption rate is found in summer (1.1 L/100 km), whereas the highest gas consumption rate occurs in winter (4.0 L/100 km). Intermediate values of gas consumption rates are observed during spring (2.6 L/100 km) and fall (2.5 L/100 km).

To gain some insight as to why gas consumption rates are much higher in winter than in summer, it is useful to look at the details of my daily commute from home to work. A one-way trip is 38.5 km, and a two-way trip from home to work and then back home is 77 km. Unfortunately, there is no charging station at my workplace, so that I can only charge my car at home.

During the summer, I usually DO get the 61 km of electric range advertised in the Chevrolet specifications. In fact, I often get more than 65 km of electric range, and sometimes get over 70 km of zero emission car driving. On five daily commutes over this 3-year period, I managed to squeeze 77 km of electric range out my car and was able to park the Volt in my driveway without burning any gasoline! In the graphic below, the dashed blue line indicates that gasoline may or may not be needed for the last 20 kilometers of my summer ride back home.

In the winter, the lithium-ion batteries are not as efficient. Roughly speaking, the reduction in electric range is about 10% to 20% around 0°C, but can get as bad as 50% below -20°C.  Over three full winters, I found that depending on outside temperatures, wind and snow conditions, the Volt's 1stGen electric range can vary between about 30 km and 50 km (dashed green line below). Gasoline may or may not be required over this 30 to 50 km portion of my return trip (dashed blue line below), but will always be needed over the last 27 km of my ride back home (continuous blue line below).
In a nutshell, the two above graphics schematically explain why gas consumption rates are much higher in winter than in summer for my Chevy Volt 2015.

Someone else's situation will be different from mine with respect to
  1. distance from home to work
  2. availability (or not) of a charging station at work
  3. climatic conditions
  4. model year; Chevy Volt's electric range increased to 85 km in 2016.

1335 km-long winter trip with Chevy Volt with temperatures below 20°C.

Advocates of plug-in hybrid electric vehicles (PHEVs), of which I am, like to say that PHEVs represent a really interesting compromise. PHEVs allow one to dramatically cut gasoline consumption (hence reducing CO2 emissions) while at the same time providing peace of mind by completely eliminating electric range anxiety.

During the 2017 Christmas holiday, we drove our Chevy Volt on a 1335 journey with several stopovers to visit family and friends in the province of Québec. This family trip coincided with a polar vortex southern excursion that saw air temperatures plunging between -20°C and -25°C for the entire 4-day duration of our trip. I only drove 35 km on electric range. The remaining 1300 km were driven on gasoline power, and they explain the three red dots indicating gas consumption rates above 6.4 L/ 100 km in the topmost graphic of this post. The Volt passed the cold Canadian winter test with flying colors!


I think it's both important and urgent that we all reduce our carbon dioxide (CO2) and methane emissions in order to slow down global warming and minimize sea level rise and other adverse impacts of global warming on coastal infrastructure and ecosystems.

For most citizens, the most concrete action they can take in their personal lives in order to reduce CO2 emissions is to purchase a low-CO2 emissions car when the time comes to buy their first car or to  replace their current vehicle.

In the province of Quebec, Canada, the average lifetime of a car is 15 years. Over that time period, this average car will have travelled some 300,000 kilometres. Imagine reducing your CO2 emissions by 65% or more over this 15-year time frame, and telling your grand-children that you did your share in the collective efforts to avoid runaway greenhouse warming!

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