Short answer? It depends on your motor and the kind of biofuel you’re thinking of.
If your car was made after 2002, there’s a very good chance you can fill up with E10 – that’s standard petrol with 10% ethanol – and drive off without a single hiccup. In fact, most cars on UK roads today sip E10 every week without even knowing it. The changeover happened quietly, and the engines didn’t grumble.
But if you’re thinking about going greener by using pure biofuels, like 100% biodiesel or E85 (85% ethanol), it’s not so simple. That stuff’s a different beast entirely. Pure biofuels can be tougher on certain engine parts, and not every motor is up to the job without a bit of help. You might need a few tweaks under the bonnet—or even a full conversion kit—before you make the switch.
So, can your car run on biofuels? If it’s E10, probably yes. If it’s the stronger stuff, not without some changes. That’s where it gets technical, and possibly a bit pricey too. But don’t worry, we’ll break it all down. From what these fuels actually are, to whether your car is a likely candidate, and what you’d need to pay if it’s not.
Let’s have a proper look at what it all means.
What Exactly Is Biofuel?
E10 and Beyond – Not All Biofuels Are Equal
Biofuels come from plants, not petroleum. Think sugarcane, corn, or even old cooking oil. That’s their eco-appeal. But how they’re blended and used varies widely.
The fuel you’ll find at most UK forecourts is E10 petrol, which contains 10% bioethanol – an alcohol made from plants – mixed with regular petrol. It’s been the UK standard since 2021. It’s designed to work with most modern engines and doesn’t require any changes to your car.
Then there’s E85, a fuel with up to 85% ethanol. Much greener, yes, but it’s not widely available in the UK and definitely not suitable for all engines. Cars need to be “flex-fuel” or specifically modified to handle that much alcohol.
And let’s not forget biodiesel. This is made from vegetable oils or animal fats. You’ll find B7 at the pump – 7% biodiesel blended with standard diesel. Most diesel cars don’t notice the difference. But if you’re eyeing pure biodiesel (B100), that’s a different story. It’s thicker, less refined, and might clog or corrode parts if your vehicle isn’t prepped for it.
2002: The Magic Cut-off Year
Why Most Post-2002 Cars Are Good To Go With E10
Here’s a simple rule of thumb: if your car was built after 2002, it’s likely E10-ready.
Car makers started preparing for biofuel compatibility back in the early 2000s. Fuel standards were shifting, and manufacturers got ahead of the curve. That means most petrol cars made since then can run on E10 without trouble.
The government even published a list of E10-compatible cars to help drivers when the switch happened. Unless your motor’s a rare classic or something from before the noughties, you’re probably in the clear.
If you’re unsure, a quick check in your handbook—or a call to the manufacturer—should settle it. Diesel drivers haven’t had quite the same change with biodiesel yet, but most modern diesels can handle B7.
Thinking of running your car on E85 or B100? That’s when things get more serious.
Pure Biofuels: Check With The Manufacturer First
Why You Can’t Just Fill Up And Hope For The Best
It might feel tempting to go all in on biofuels for the sake of the planet, but here’s a word of caution: don’t do it without checking with your manufacturer.
Not all engines are built for high-percentage biofuels. E85 and B100 can cause damage over time. Rubber hoses, gaskets, seals, and even injectors might degrade, corrode, or clog up.
Flex-fuel vehicles – mostly seen in Brazil and the US – are made to switch between regular petrol and high-ethanol fuels with no problem. They’ve got special sensors and fuel system components designed to cope with ethanol’s quirks.
UK cars? Most aren’t flex-fuel. A few might be, but unless it says so clearly in the manual, you need to ask. Otherwise, you risk expensive repairs down the line.
Biofuel burns differently. It can leave behind residues, it absorbs water, and it behaves oddly in cold weather. A standard fuel system may simply not be ready.
Modifying Your Car To Run On Pure Biofuels
What Needs Changing And How Much Might It Cost?
Alright, so you’ve spoken to the manufacturer and they’ve said: “No, your car isn’t built for E85 or B100.” But you’re still keen. Can you modify your car to make it work?
Yes, in many cases, you can convert your car to run on higher concentrations of biofuel. But there’s a price tag attached.
For E85 (Petrol Cars):
To run on E85, you may need:
- Ethanol-compatible fuel lines and gaskets
- A flex-fuel sensor to detect ethanol levels
- An ECU (Engine Control Unit) remap or upgrade
- Possibly a new fuel pump and injectors
This kind of conversion could cost between £700 to £1,500, depending on your car and the quality of parts. Some drivers install aftermarket flex-fuel kits, which automatically adjust engine timing and fuel-air ratios based on ethanol content.
For B100 (Diesel Cars):
To safely use B100, expect to replace or upgrade:
- Fuel filters (more often, too – biodiesel cleans your fuel system, which can clog filters fast)
- Fuel hoses and seals (older ones may not be biodiesel-compatible)
- Possibly the fuel tank if it’s prone to corrosion
- The fuel injection system if it’s sensitive to thicker fuels
Conversion costs vary widely but usually start around £500, rising to £2,000 or more for complex diesel systems. Regular maintenance is also key. Biodiesel likes to gel in cold weather, so you may need tank heaters if you’re in chilly parts of the UK.
Not every garage will handle biofuel conversions, so make sure you find a mechanic with real experience in this area.
Should You Make The Switch?
The Pros And Cons, Laid Bare
There’s no doubt biofuels are better for emissions. Ethanol and biodiesel burn cleaner, with lower CO₂ outputs than their fossil fuel cousins. Plus, they’re renewable – made from crops, waste oils, and even algae.
Pros:
- Reduced carbon footprint
- Supports local agriculture and waste recycling
- Often cheaper (if you can find it!)
- Can improve engine lubrication (especially biodiesel)
Cons:
- Compatibility issues
- Reduced fuel economy (especially with ethanol – it has less energy per litre)
- Limited availability across the UK
- Cold weather problems
- Upfront modification costs
For most UK drivers, E10 is the easiest green choice. No changes needed, easy to find, and relatively clean. If you’re passionate about biofuels and don’t mind a bit of investment, E85 or B100 could be viable – but don’t rush in blindly.
Final Thoughts – Know Your Motor Before You Go Bio
The idea of fuelling your car with something grown in a field or scooped out of a fryer might sound a bit mad, but it’s real—and it works. The key thing is knowing what your car can handle.
For the vast majority of drivers in the UK, E10 is already under the bonnet, doing its bit for the planet. No fuss, no faff. But if you’re thinking about going further—using pure biofuels—you’ve got to do your homework.
Check the year your car was built. Ask your manufacturer. And if you’re serious about going fully green, be ready to spend a bit on upgrades. Biofuels are brilliant, but only when your motor’s ready for them.
So yes—your car can run on biofuels. But how far you go, and how much you need to change, depends entirely on your model, your fuel type, and how deep your eco ambitions run.
