Originally Posted by
elnevio
From the factory they are designed to run on 100 RON petrol. The closest readily available to that is Tesco's Momentum 99, although most people's number one choice is Shell V-Power. The octane rating of petrol is essentially a measure of its resistance to knock/detonation which is more likely to occur with regular unleaded. The ECU will detect this and pull the timing to protect the engine. The real-world effect of this will be a reduction in power, perhaps in the order of 25-30 ponies! :o