CARS - 25.02.2021

Why are plug-in hybrids under scrutiny?

Plug-in hybrids are marketed as greener than a petrol or diesel equivalent, but without the range limitations and price tag of pure electric. But research has now claimed they are a bit of a con. What’s the story?

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Hybrid cars can run on electric as well as petrol or diesel. In full or self-charging hybrids the battery is charged using energy recuperated when braking or coasting.

Plug-inhybrids (PHEVs) have a larger range on full electric, up to 40 miles or more in some cases depending on the speed you are driving and other factors, such as wind, vehicle weight, etc. To charge the battery they need to be plugged in. PHEVs are an increasingly popular choice for SMEs given that they’re green and have low emissions and can deliver fuel savings. There are tax savings too.

A September 2020 survey of businesses with fewer than 100 staff showed that 46% either have a PHEV or plan to add some to their fleet. This compares to 28% in 2019. For hybrids the figures were 45% and 37% respectively.

The incentives for PHEVs have been gradually reduced, however. In 2018 the government removed PHEVs that didn’t do at least 70 zero emissions miles. This is to encourage pure electric.

End of the road?

PHEVs are now under intense scrutiny. A report in September by campaign groups Greenpeace and Transport & Environment showed the cars emit 2.5 times more CO2 in “real world” conditions than in lab tests (see The next step ).

As the table shows, the data pulled together in the research shows PHEVs are still better than pure combustion engines but they found the cars had flaws, e.g. switching from electric in colder temperatures, that inhibited their benefits. The fuel consumption figures also won’t be as attractive. But there was a bigger problem causing higher costs and carbon.

Engine Lab test CO2 emissions (gCO2 /km) Real world emissions (gCO2 /km) CO2 emissions (tonnes/year)
Diesel 118 167 5.2
Petrol 120 164 5.1
Self-charging hybrid 92 136 4.3
PHEV 44 117 3.6
Full electric 0 0 0.7

An inconvenient truth

The main issue was that people were not charging them up. Research in Germany published in September 2020 by the International Council on Clean Transportation found the same. Private users charge their PHEVs an average of three out of four driving days. For company cars, charging took place only about every second driving day (see The next step ).

Tip. If you are thinking about buying a PHEV make sure there is easy access to a charging point for staff. If you have PHEVs in the company, remind staff to charge them up. This will save on fuel as it will run in electric mode - which is the whole point of buying one.

Tip. Think carefully about the type of driving you will be doing. Long miles on the motorway in a PHEV will offer scant returns.

For a link to the research, visit https://www.tips-and-advice.co.uk , Download Zone, year 15, issue 9.

The efficiency and emissions benefits are not as good as the claimed figures. But this isn’t only down to manufacturers. Research shows that company hybrids are only charged every other day. Make sure staff with access to the cars know they need to be charged after use and carefully consider the type of driving you are doing.

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