For an ordinary petrol or diesel built for 95 RON / standard diesel, premium fuel won't make a measurable difference to performance or economy on a single tank. But running a tank of premium every 3,000 miles helps keep injectors and intakes clean, and that's worth doing. Daily premium use is wasted money in 95% of cars.
Bob's honest take on the most googled fuel question in the UK.
Will premium fuel give me better MPG? — On a car designed for 95, no — independent tests show no meaningful MPG difference. On a car designed for 98 running on 95, yes — switching to premium will recover the MPG you've been losing.
Is supermarket fuel bad for my car? — No. UK supermarket fuel meets the same EN228 (petrol) and EN590 (diesel) standards as branded fuel. The difference is in the additive package — supermarket fuel typically has a leaner cleaning package.
What about fuel system cleaner additives in a bottle? — A decent PEA-based cleaner (Redex Petrol System Cleaner, BG44K, Wynn's) once a year does roughly the same job as a tank of premium and costs less. Either approach is fine; doing both is overkill.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].