Mercedes-Benz Responds To Viral E20 Mileage Row: Can Ethanol-Blended Petrol Really Slash Fuel Efficiency?

A fresh debate around India’s E20 petrol rollout has erupted after popular YouTuber Sourav Joshi claimed that the fuel efficiency of his Mercedes-Benz GLC dropped dramatically after refuelling with E20 petrol. The viral claim prompted an official clarification from Mercedes-Benz India, which reiterated that all of its BS VI petrol vehicles sold in the country are fully certified and compatible with E20 fuel.

While the incident has reignited concerns among motorists about ethanol-blended fuels, industry experts point out that fuel economy is influenced by numerous variables and that a sudden mileage collapse cannot be attributed to E20 fuel alone without a detailed technical diagnosis.

What Triggered The Controversy?

According to the viral video, Sourav Joshi claimed that his Mercedes-Benz GLC’s fuel efficiency reportedly dropped from around 16-17 km/l to nearly 5 km/l shortly after filling E20 petrol. He also expressed concerns about possible engine damage and reportedly planned to have the SUV inspected at an authorised Mercedes-Benz service centre.

The video quickly gained traction across social media, sparking fresh discussions around the government’s ethanol blending programme.

Mercedes-Benz India Issues Official Clarification

Mercedes-Benz India responded by stating that:

• All BS VI petrol-powered Mercedes-Benz models sold in India are fully compatible with E20 petrol.

• These vehicles have been engineered, tested and certified to operate safely on E20 fuel.

• Fuel efficiency depends on several factors including driving style, traffic conditions, tyre pressures, vehicle load, ambient temperature and overall vehicle condition.

• The company remains available to inspect any customer’s vehicle to identify the actual cause of abnormal fuel consumption.

Notably, Mercedes did not confirm that E20 petrol caused the reported mileage drop and instead indicated that the vehicle should undergo proper diagnostics before any conclusions are drawn.

Can E20 Petrol Reduce Fuel Efficiency?

Yes—but only to a limited extent.

Ethanol contains approximately 30-35% less energy per litre than conventional petrol. Since E20 contains up to 20% ethanol, vehicles generally experience a 3-5% reduction in fuel efficiency compared to pure petrol, depending on engine calibration and driving conditions.

A reduction from 17 km/l to 5 km/l, however, represents nearly a 70% drop, which is far beyond what would normally be expected solely due to ethanol blending.

What Else Could Cause Such A Mileage Drop?

Automotive engineers suggest several possibilities that should be investigated before blaming the fuel itself:

• Faulty oxygen (O2) sensor

• Malfunctioning mass airflow (MAF) sensor

• Incorrect air-fuel mixture

• Fuel injector issues

• Ignition system problems

• ECU calibration anomalies

• Tyre pressure changes

• Heavy traffic or prolonged idling

• Transmission or drivetrain issues

• Fuel contamination unrelated to ethanol percentage

A complete diagnostic scan would be required to determine the actual cause.

Understanding India’s E20 Programme

India has accelerated its ethanol blending programme to reduce dependence on imported crude oil while improving energy security.

The government has highlighted multiple benefits, including:

• Lower crude oil imports

• Reduced carbon emissions

• Additional income for sugarcane farmers

• Better utilisation of agricultural surplus

• Savings in foreign exchange

Government data indicates that the ethanol blending programme has already generated significant economic benefits while supporting domestic agriculture.

Auto Punditz Analysis

This episode once again highlights how quickly isolated incidents can shape public perception around new automotive technologies.

While E20 petrol can result in a small reduction in mileage, current technical evidence does not support the claim that it can independently reduce fuel efficiency by nearly 70% in a properly functioning BS VI vehicle.

Mercedes-Benz’s response is also significant because premium manufacturers have invested heavily in ensuring their BS VI petrol engines comply with India’s E20 roadmap. Similar compatibility statements have been issued by several other OEMs over the past two years.

Ultimately, only an official technical inspection of the specific Mercedes-Benz GLC involved will establish the root cause of the unusually high fuel consumption.

Until then, it would be premature to conclude that E20 petrol alone was responsible.