The ethanol threat to classic cars and bikes In the US at least, things changed in the wake of the 1970s fuel crises, when the economic risk of relying on imported fossil fuel became clear. Hence a sudden interest in "renewable resources," which involved swathes of land being used to grow crops that would ultimately be eaten by engines, rather than people. Gasohol, a blend of petrol and "bio-ethanol" produced by fermentation, was touted as the fuel of the future. However, once relative stability returned to crude oil prices the notion became less attractive. Apart from shortcomings ethanol has as a fuel, the problem is that its production uses lots of energy (and water). Corn-based fuel, as in the US, is energy-negative by the time it comes out of a pump. Given the right climate, other crops, particularly sugar cane, are much better, which explains why Brazil leads the world in ethanol use. Since the 1970s, vehicles have been available that will run on 20 per cent alcohol and above. Yet ethanol is also a powerful solvent that, without a suitable additive, attacks many fuel system components including zinc and galvanised materials, brass, copper, aluminium, seals and hoses, cork, polyurethane and epoxy resins. In other words, almost everything used in a vehicle made more than about 20 years ago. It's also hydrophilic, and water causes all sorts of additional problems. Which brings us back to the sagging fuel tank incident. Old GRP mouldings, like the curvaceous receptacle fitted to my 1967 BSA, are particularly under threat. The internal sealants applied to steel tanks are also affected, as are the plastics used in modern bikes. In the US, where E10 gasohol is universal, lawsuits are flying. Ducatis have been affected, as have boats and agricultural machinery. Expect more of the same, because E15 (15 per cent ethyl alcohol) received government blessing last year and there's evidence that even relatively recent cars might find it hard to digest. In the UK, oil companies are coy about saying which petrol contains ethanol, so owners of classic vehicles have to find out the hard way. Many old and not so old vehicles will be unusable without modification (the DfT puts the figure at 8.6 million if E10 is introduced). No doubt this will be welcomed by those who believe that throwing things away every few years will somehow save the planet, but it's a worrying development for the rest of us and another nail in the coffin for classics.