What is the difference between the cheapest fuels in a place like Tesco's and the 'high quality', highly priced competitors? Is there actually any noticeable difference in available power, engine smoothness, efficiency, maintenance costs etc?
Personally I've always used the cheapest I can just because I don't know what the difference is that I would be paying for!
Can anyone justify their use of an expensive fuel having had a bad experience with a cheap fuel in their car in the past?
Gasoline is made in large batches. Each batch has a number of attributes that should be met; Octane, specific chemistry, volatility, contaminates, ethanol content, and others. The output is dependent on the crude that went into the refinery and the processes the refiner has at hand to process it. Refineries vary in there capabilities.
There are over 60 different fuel variations required by government regulation in the US. These are formulated to help with air pollution concerns that vary by region, mostly, but not always due to average weather conditions. Regulators require an average quality across many batches. So that means there are batches that do not meet standard. These are often purchased by low price marketers who then pass on the "savings". Batches are often in the 2 million liter range. Also the brand specific detergent additives are put in at the truck level only in those loads headed for specific retail stations. These additives are expensive and usually not used in the thrift-ed brands.
So yes, there are many differences and the answer is, as is often the case, It Depends!
As far as I understand it, the 'premium' brands will have the fuel mixed to their own specifications, which may include particular detergents, additives etc. The cheaper brands will simply buy whatever is cheapest - so the Tesco one could be identical to Shell one week (if Shell happened to have a surplus), BP the next, a mixture of things the week after, and so on. As Fed Wilson says, often they will by the stuff that didn't make the grade for the premium suppliers.
So as Fred says, 'it depends' - but the premium fuel will be more consistent, generally.
Depends on your vehicle. Most are tuned to use regular fuel, which hovers around the 87 octane rating. If your vehicle is turbo or supercharger then it should use a higher octane rating. Refer to the user's manual.
Real difference? None. Some sell fuel with additives that "help" with keeping your fuel system "clean". But I have never seen any difference.
