Fuel saving theory and operational reality
Externally charged hybrid vehicles, also known as plug-in hybrids, have long been considered a reasonable intermediate step between traditional hybrid vehicles and pure electric vehicles. The operating idea is quite simple: users travel short distances by electricity and use an internal combustion engine for long journeys. However, actual use is showing a large gap between theory and practical results.
A large-scale study conducted by the Fraunhofer Institute of Germany analyzed data from 981,035 plug-in hybrid vehicles manufactured in the period 2021 - 2023. Data was collected through a fuel consumption monitoring system on vehicles. The results showed that the actual fuel consumption was more than three times higher than the laboratory test parameters according to the Worldwide Harmonized Light Vehicles Test Procedure cycle.
According to certification data, a plug-in hybrid car consumes an average of about 1.57 liters of gasoline per 100 km. However, when operating in reality, the consumption increases to 6.12 liters/100 km. Even when the car operates in electric priority mode, the consumption is still around 2.98 liters/100 km.
The results also show a clear difference between car manufacturers. Some high-performance plug-in hybrid models of Porsche have a real consumption of about 7 liters/100 km. Meanwhile, many models of Kia, Toyota, Ford and Renault recorded significantly lower consumption in the same conditions.
Not charging the battery often, the biggest mistake
According to researchers, the most important reason for this difference is the usage habits of users. Many plug-in hybrid car owners do not charge the battery as often as the car is designed to operate.
Research data shows that plug-in hybrid cars owned by individuals only operate on electricity for about 45-49% of the time. For company cars, this rate is even lower, only about 11-15%. Meanwhile, the experimental model in the laboratory assumes that the electricity operation rate can reach 70-85%.
Mr. Patrick Plötz - a research expert at the Fraunhofer Institute, said that internal combustion engines on many plug-in hybrid cars operate more frequently than manufacturers expect. This happens even when the driver claims that the car is running mainly on electricity.
When the battery is not charged, the plug-in hybrid car is forced to rely more on the internal combustion engine. At the same time, this engine also has to "carry" a heavy battery block, causing fuel consumption to increase significantly.
Experts also point out other factors such as cold weather, high speed or long journeys exceeding the daily electricity running range also reduce fuel efficiency.
In general, plug-in hybrids can still save fuel more efficiently than traditional hybrid cars, but only if users maintain the habit of charging the battery regularly and operating the car properly.
