This article was published by the Canada Energy Regulator on Nov. 3, 2021.
Plug-in hybrid-electric vehicles (plug-in hybrids) are like regular hybrid-electric vehicles (regular hybrids): they have an internal-combustion engine (ICE) and one or more electric motors powered by a battery. Both plug-in hybrids and regular hybrids recharge their batteries while the car is driving, using regenerative brakingFootnote1 and power generated by the ICE. The difference between plug-in hybrids and regular hybrids is that the batteries in plug-in hybrids are much larger and can also be charged by plugging the vehicle into electrical outlets, similar to electric vehicles. Some plug-in hybrids can drive for almost 100 kilometres (km) using their electric motors before their ICEs need to turn on.
A prior snapshot showed how electric vehicles have much better fuel economy than vehicles with internal-combustion engines (conventional vehicles) and even regular hybrids. This is because electric motors are far more energy efficient than ICEs. This also means plug-in hybrids can have much better fuel economy than conventional vehicles and regular hybrids. However, the battery only ranges of plug-in hybrids are much shorter than the ranges of electric vehicles. This means the fuel efficiency of plug-in hybrids can change quite a bit: if a plug-in hybrid can drive only on battery power most of the time, it can have very good fuel efficiency. If the plug-in hybrid needs to use its ICE a lot (for example, because it typically drives trips much longer than its battery only range) its fuel efficiency worsens.
Figure 1 below shows the battery only ranges for plug-in hybrids for sale in Canada in 2021. These range from 24 km to 98 km, though most vehicles range from 24 km to 50 km. Most Canadians have short commutes (17.4 km for a round-trip), which is below Figure 1 ranges. This indicates most Canadians could use a plug-in hybrid to drive battery only for most of, if not all, their daily needs.
Figure 1: Battery only ranges in plug-in hybrids for sale in Canada in 2021
Figure 2 below shows estimated, average fuel efficiencies for plug-in hybrids in litres equivalent per 100 km (Le/km), assuming vehicles drive combined city and highway drivingFootnote2 as battery only until they drain their batteries. After they drain their batteries, they drive combined city and highway driving as regular hybrids, using their ICEs and electricity stored in their batteries during regenerative braking for the rest of their trips.Footnote3 For short trips (50 km or less), fuel efficiencies are much better than longer trips (200 km or greater) for all plug-in hybrids. It is important to remember these are average values across models within vehicle classes. A key factor in how far a vehicle can drive while consuming much less fuel is its battery only range, which often varies a lot within a vehicle class, as shown in Figure 1. Meanwhile, the fuel economies of different models can also be very different even when in the same vehicle class.
Figure 2: Average efficiency for plug-in hybrids for sale in Canada in 2021 by vehicle class and by distance driven between recharging
Figure 3 below compares the averageFootnote4 fuel efficiencies of plug-in hybrids to the average fuel efficiencies of conventional vehicles, regular hybrids, and electric vehicles for sale in Canada in 2021, with the option to change the driving distance between when the plug-in hybrids are recharged. Conventional vehicles, regular hybrids, and electric vehicles do not change fuel efficiency by trip distance, because each has only one fuel type (gasoline or diesel) that needs refuelling, unlike plug-in hybrids. For trips of 25 km, plug-in hybrids generally have fuel efficiencies almost as good as electric vehicles, meaning they are very fuel efficient compared to the entire vehicle fleet. For longer trips between recharging, the fuel efficiencies of plug-in hybrids quickly approach and are sometimes worse than regular hybrids. This is largely because some manufacturers are building plug-in hybrids based on some of their more powerful and fuel inefficient conventional vehicles. These plug-in hybrids have fuel efficiencies for long-distance trips not as good as many regular hybrids, which tend to be built with smaller and more fuel-efficient engines even when in the same vehicle class as the plug-in hybrids.
Figure 3: Average, combined city and highway fuel efficiencies for conventional vehicles, regular hybrids, plug-in hybrids, and electric vehicles for sale in Canada in 2021, including by distance driven before recharging for plug-in hybrids
Footnote 1: Regenerative braking uses magnets inside a regular hybrid’s, plug-in hybrid’s, or electric vehicle’s electric motor to slow the vehicle instead of using disc brakes on the vehicle’s wheels. These magnets convert motion to electricity, which can then be stored in a car’s battery as the car slows.
Footnote 2: Efficiencies vary by driving style: city driving is largely at lower speeds, but with periods of braking at stoplights and stop signs. Plug-in hybrids, regular hybrids, and electric vehicles tend to have better fuel efficiency when city driving because regenerative braking conserves energy from slowing and stopping in the vehicle’s battery. Highway driving is at higher speeds but with less braking. Plug-in hybrids, regular hybrids, and electric vehicles tend to have worse efficiency at highway speeds because of higher wind and rolling resistance.
This is opposite to conventional vehicles. Conventional vehicles have worse fuel efficiencies when city driving, because energy is lost during braking. Meanwhile, they have better fuel efficiencies when highway driving, because they do not brake nearly as much (and less energy lost from braking is more than enough to make up for energy losses from increased wind and rolling resistance when driving at highway speeds).
See Natural Resources Canada’s 2021 Fuel Consumption Guide for more information on how vehicles are tested. Note: while the Fuel Consumption Guide has city, highway, and combined fuel efficiencies for conventional vehicles, regular hybrids, and electric vehicles, their information for plug-in hybrids is more limited. The guide has city, highway, and combined fuel efficiencies for plug-in hybrids driving in regular, hybrid mode (i.e., after the battery is exhausted), but only has combined fuel efficiencies for battery only driving.
Footnote 3: The fuel efficiency of a plug-in hybrid over a set distance driven is calculated by dividing the total Le of fuel consumed over a trip then dividing by trip distance. In other words, plug-in hybrid fuel efficiency by distance, or PFED = (Min(b,d)*BFE/100 + Max(d-b,0)*HFE/100)/(d/100), where: b = battery range (km), d = trip distance (km), BFE = battery only fuel efficiency (Le/100 km), and HFE = hybrid-mode fuel efficiency (Le/100 km).
Footnote 4: This is the average value for all models available, not a weighted average that considers not only the number of models, but how many of them are sold.