In short, no, if you normally use regular unleaded (as opposed to super-unleaded). As we’ve already touched on, the amount of power and torque that can be released by the fuel is dictated by the octane rating. Put simply, the higher the number, the more energy you’re going to get.
This means that if you’ve been using standard (or ‘premium’ in fuel company marketing speak) unleaded with a 95 RON (it stands Research Octane Number, so now you know) then you should notice no drop off in your car’s performance in the switch to E10.
However, if you’re currently using super-unleaded, which, in the UK at least, features a rating of between 97 and 100 RON, then swapping to E10 will have a small but detrimental effect on both performance and efficiency. Saying that, we’re talking about a drop of only a few horsepower (very definitely single digits), so outright urge will be very similar.
What is likely to be more noticeable is the slightly dulled throttle response, with regular users of super-unleaded often reporting their car ‘feels’ more responsive, especially in the low to medium ranges. That could be a placebo effect of course, but many independent studies have revealed the modest gains that can be gleaned from higher-octane fuels, with testers reporting subjective improvements on the road.
So should I use E10 petrol in my performance car?
If your car’s user manual says it’s compatible with this type of fuel, then there’s no reason why you shouldn’t use it. Apart from the drop in fuel economy compared with the E5 alternative, there should be no difference at all in the way your car drives.
That said, if you want to make sure you’re getting the most out of your car’s engine in terms of performance and fuel efficiency, then super-unleaded is still the way to go. In fact, when it comes to high-performance models, most manufacturers recommend that you should use a fuel with a minimum octane rating of 98 RON, which like all higher-grade petrols is still an E5 blend.
Yes, it’s more expensive to buy, but factor in the increase in efficiency over 95 RON unleaded, particularly E10, and the cost difference in the long run is likely to be negligible.