This has raised concerns among many vehicle owners, particularly those driving older car models.

E10 biofuel is a blend of 90 percent RON95 gasoline and 10 percent ethanol (E100), a bio-alcohol typically produced from corn, cassava, sugarcane, or other agricultural by-products. The shift to biofuel is seen as an important step to cut emissions, ensure energy security, and reduce dependence on fossil fuels.

On many car owners’ forums, there have been numerous comments claiming that vehicles seem to become more sluggish, consume more fuel, and even develop minor faults after using E10. Although most of these reports are anecdotal and lack full verification, they still leave many owners uneasy, particularly those with older cars.

The primary concern for most people is the compatibility between E10 gasoline and car engines. Many owners worry that their vehicles will experience reduced performance, consume more fuel, or suffer long-term damage to the durability of their fuel delivery systems. 

So, is it true that E10 gasoline makes engines "weak and sluggish" as many fear?

Speaking with VietNamNet, Assoc. Prof. Dr. Dam Hoang Phuc, director of the Automotive Engineering Training Program at Hanoi University of Science and Technology (HUST), said that due to its composition, the use of E10 gasoline has an impact on engine power output.

A research team at HUST, led by Phuc, conducted tests and measurements on the operation of cars using different fuel types, including RON 95-V, E5 RON 95-V biofuel, and E10 RON 95-V gasoline.

The research on the Toyota Corolla Cross model showed that E10 gasoline yielded the lowest power output among the three fuel types across all speed ranges from 60 to 120 km/h, for both the purely gasoline-powered version and the hybrid version. The performance discrepancy compared to A95 and E5 gasoline hovered around 1-5 percent.

This impact on engine efficiency also makes cars running on E10 gasoline slightly more "sluggish" than those on other types of gasoline. 

Specifically, the acceleration time from 10 to 100 km/h for E10 gasoline on the pure gasoline and hybrid variants was 10.49 and 9.19 seconds, respectively. The figures for A95 and E5 gasoline were 9.62 - 9.21 seconds and 8.56 - 8.13 seconds, respectively.

Phuc noted that while the study was conducted on only one vehicle model, it highlights both the environmental advantages and certain drawbacks of biofuel, including E10 gasoline, which is drawing significant public attention at this time.

According to experts, the difference in engine power output is minor and difficult to notice under normal driving conditions. However, the greatest risk does not lie within the E10 gasoline itself, but rather in using the wrong fuel for the vehicle. Users need to check which Euro emission standard their vehicle meets and whether it supports E10 fuel.

Experts point out that for newer car models, especially those meeting Euro 4 or Euro 5 standards, the vast majority have been designed by manufacturers to be compatible with biofuels. Many models even have clear labels such as “E10” or “E20” printed directly on the fuel tank cap. 

On the other hand, very old car models, particularly those that have been in use for over 20 years and lack an “E” mark on the fuel cap, require a more thorough inspection before switching to E10.

What should owners of older cars keep in mind?

According to experts, the ethanol in E10 gasoline has hygroscopic properties (moisture-absorbing) and acts as a solvent. Therefore, for car models that have been on the road for decades, especially those not originally designed for biofuel compatibility, experts warn of risks affecting rubber gaskets, seals, or fuel lines.

They recommend reviewing the entire fuel system, including hoses, rubber gaskets, fuel pumps, and injectors, to prevent material degradation caused by long-term exposure to ethanol.

Le Thuong Tien, director of Auto's Only Service Workshop in HCMC, believes that car users switching to E10 gasoline do not need to be overly anxious, but must keep in mind proper usage methods, particularly for vehicles that are rarely driven.

He said if a car is not used regularly and a single tank of gas lasts for more than two weeks, users should avoid filling the tank to the top.

The reason is that ethanol in E10 absorbs moisture. Although anti-water separation additives are blended into the fuel, storing it for too long still poses a risk of moisture accumulation inside the fuel tank. This can adversely affect the car's fuel injection system and injectors.

Hoang Hiep