Often, though, super-unleaded E5 petrol is considerably more expensive than standard E10 petrol. It's a premium fuel and is typically around 10p per litre more than standard petrol. Generally, if your car is fine to run on E10 fuel, it'll be cheaper to run on E10 than on E5.
What is the price difference? E10 is essentially a greener fuel, and as a result, it pays less environmental penalty, around 1p a litre less. That basically means it's cheaper upfront. However, as E5 is only available in premium, or super unleaded, drivers who opt for it have to pay a premium charge.
Regular petrol is generally the greener option
At the unleaded pumps you'll normally see two options: regular, or E10, and a premium option labelled E5. E10 means there is 10% ethanol in the fuel mix; E5 means 5%. If you only look at mileage per pound, the premium shouldn't have any advantage.
Where E5 is 95 percent unleaded petrol and five percent ethanol, E10 is 90 percent unleaded petrol and 10 percent ethanol. “Ethanol is made during the fermentation process of some crops such as sugarcane and grain, this means it is a more sustainable fuel as it is coming from a renewable source.
Often, though, super-unleaded E5 petrol is considerably more expensive than standard E10 petrol. It's a premium fuel and is typically around 10p per litre more than standard petrol. Generally, if your car is fine to run on E10 fuel, it'll be cheaper to run on E10 than on E5.
“And those with E10 compatible cars will unfortunately find they are getting fewer miles to the gallon as the fuel is less efficient than E5 fuel, due to it containing 5% more ethanol.
E10 can damage older cars
It's well-established that the higher ethanol content of the fuel can: corrode a variety of engine parts, including “rubber parts, gaskets, seals, metals and plastics“ cause deposits to shift within susceptible engines and fuel systems, potentially resulting in blockages.
If your vehicle is compatible with E10 petrol, there's no reason you can't mix the 2 grades of petrol (E5 97+ and E10 95+). It's perfectly safe to mix them in the same tank or fill up with E5 if E10 is not available.
What's the problem for classic cars? Although many cars run on E5 without significant problems, doubling the amount of ethanol in the fuel can cause a variety of issues in olders cars. Ethanol is hygroscopic, which means that it absorbs water from the atmosphere. And that water, in turn, finds its way into your car.
Do I get the same fuel economy out of E10 as regular unleaded petrol? At the pump, E10 is generally the cheapest petrol per litre. Because the energy provided by the ethanol is less than the energy provided by pure petroleum, E10 has around 3% less energy than the equivalent amount of RON 91 petrol.
All models since model year 2005 are suitable for use with E10. If your car is older than 2005, then you should carry on using E5.
E10 is considered a less stable fuel than E5, which could lead to starting issues in some vehicles.
As mentioned above, all vehicles made after 2010 can run on E10 fuel and the majority of cars built between 2002 and 2010 will also be compatible. However, there are some exceptions, including certain models from brands like Ford, Renault, Toyota, Lexus, Volkswagen, Audi and Mercedes.
CAN I MIX E10 AND REGULAR UNLEADED? Not like diesel and petrol, you can refuel with E10, regular or premium unleaded without any damage to the fuel system or engine.
Therefore, if your classic is not used for a while, it is advisable to refuel a premium gasoline with the lowest possible alcohol content (Super 98, V-Power, Excellium, etc.). Some suppliers are offering additives for E10, specially designed to counteract the harmful effects on our classics.
The storage life of petrol is one year when stored under shelter in a sealed container. Once a seal is broken the fuel has a storage life of six months at 20°C or three months at 30°C. The storage life of petrol in equipment fuel tanks is one month.
But using E10 petrol in an incompatible vehicle will, over time, cause problems in the fuel system. Carburettor corrosion, fuel hose degradation, fuel filter blockage and damaged fuel pumps are all likely if you use E10 regularly in vehicles that shouldn't take it.
"E10, due to its higher bio-ethanol content, actually burns off faster than E5, meaning less mileage is gained from filling up with E10 meaning more cost for motorists." The expert also urged drivers to be careful when opting for E10 petrol as some vehicles might not be compatible with the fuel.
The problem appears to be significant. It is believed that the higher bioethanol content in E10 petrol could dislodge deposits in older engines and fuel systems, causing blockages; it could also cause some seals, gaskets, metals and plastics to corrode.
E10 is an ethanol-based fuel, in that it's 10% ethanol and 90% unleaded petrol. It has a higher octane rating of 94, which could result in better performance if your car is tuned for it.
While a car not designed to run on E10 will likely not suffer engine damage, the ethanol can damage fuel lines and other parts of the fuel system, leading to longer term problems. E10 emissions can also damage the core of catalytic converters.
Most standard unleaded fuels have a 95-octane rating, but premium fuel has a higher rating (around 98-octane) but is more expensive to produce, hence the higher price.
Ethanol has lower energy content than petrol, so generally speaking it provides less 'bang for your buck'. ABMARC says this means that you probably won't drive quite as far on a tank of E10 as you would on a tank of unleaded (91 RON) or 95 RON.
“The energy content of ethanol is about 33% less than pure unleaded... economy varies depending on the amount of denaturant that is added to the ethanol. In general, vehicle fuel economy may decrease by about 3% when using E10”.
Those vehicles manufactured before 2002 were not designed to operate with such high ethanol content fuel and as a result, could be damaged by using E10.