Surprisingly, your car would probably run on E85, but it wouldn’t run properly. E85 is 85 per cent ethanol (and 15 per cent petrol) which has a lower energy content than straight petrol. As a result, a car running on E85 will need to use up to 30 per cent more fuel by volume to work properly. As your car is not tuned for this, it would probably run but would be down on power and may not idle or accelerate smoothly.

The bigger issue is that the high ethanol content fuel can be corrosive to fuel system parts (pumps and lines) not designed for it. While many Subaru models are, in fact, compatible with and suitable for E10 fuel (10 per cent ethanol and 90 per cent petrol) E10 has an octane rating of 94 while your car requires a minimum of 95-octane fuel. So even E10 would be a no-no.

With all that in mind, I think the best advice would be to drain the tank of the E85 as soon as possible. Refill it with 98-octane petrol and go for a drive to purge any residual E85 form the lines. Your workshop may even suggest a new fuel filter. If they don’t, ask about it yourself. The good news is that it’s very unlikely you’ve done any damage beyond the dent you’ve just put in your wallet.