A nationwide LocalCircles poll of over 36,000 responses across 323 districts reports that 8 in 10 owners of vehicles bought in 2022 or earlier have seen a drop in fuel efficiency after switching to E20 petrol.
The share of affected owners rose through the year, from 67 percent in August to 80 percent by October. The same survey says 52 percent of these owners also faced unusual wear or repairs in 2025, often around fuel system components, engine internals and in some cases tanks.
The data arrives in the first year after E20 became mandatory across the country in April. The survey does not quantify the exact kilometre-per-litre loss for each model, but the pattern is strong enough to treat as a real-world signal rather than noise.
Ethanol is hygroscopic, which means it absorbs moisture from the air. In older vehicles with unprotected steel tanks or ageing fuel lines, that moisture can accelerate corrosion.
Ethanol can also swell or harden certain rubber compounds used in older hoses, seals and gaskets. Modern engines and fuel systems are designed with higher ethanol blends in mind and use materials that resist these effects. Many older designs and parts do not.
That gap shows up as a small but steady mileage dip and, for some owners, a rise in maintenance events such as clogged injectors, softened hoses, failing seals or fuel pump noise.
Energy density also plays a part. Ethanol has fewer joules per litre than pure petrol. Unless an engine is mapped and built to recover the difference with timing and fuelling strategies, you will typically travel fewer kilometres per litre as blend levels rise. Newer, E20-ready or flex fuel style engines claw back much of that loss. Older engines cannot do as much.
A few simple habits help. Keep the tank reasonably full if the vehicle will sit for many days. Less air space means less moisture ingress and slower phase separation. Buy from high-turnover pumps so fuel is fresh. Replace older rubber hoses and check clamps and joints at every service.
If your vehicle uses a serviceable fuel filter, change it on time or a little early for the next couple of cycles. Owners of carburetted two wheelers should plan for occasional jet cleaning.
Watch for early signs such as hard starts after a week of parking, hesitation under load or a petrol smell near the tank area. Tackling these small flags early is cheaper than dealing with a fuel pump or injector failure later. None of this removes the blend’s effects, but it reduces the likelihood of a roadside failure and keeps efficiency closer to your baseline.
If you intend to keep an older petrol car or two wheeler for the next three to five years, set a small buffer in your running cost. Expect a modest hit on kilometres per litre and plan for a minor fuel system refresh during that period.
This could include new hoses, seals and a preventive filter or injector service. If your vehicle is newer, ask the workshop whether it is E20-certified and whether any part number updates were introduced for hoses, pumps or injectors after your build month.
Some models receive engine map updates that improve drivability on E20. It is worth asking for them during scheduled service. If you are buying now, check the brochure or ask the dealer to confirm E20 readiness in writing.
Also ask whether there are hardware differences between pre-2023 builds and current stock, and whether those changes can be retrofitted on earlier vehicles of the same model. These are straightforward checks that make ownership calmer under the new blend.
Since E20 became the norm in April, 8 out of 10 owners of 2022-or-older vehicles report lower mileage, and just over half report unusual maintenance this year.
The findings do not say E20 is unsafe for older machines. They say older hardware may cost a little more to run and maintain under the new fuel. Adjust your service routine, buy fresh fuel, refresh ageing parts and, if you are shopping today, pick an E20-ready model.
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