The dream of a vehicle fuel systems that runs on anything, like Back To the Future's Mr Fusion, is getting closer to a reality. Two military stealth bikes have been shown off that not only run near-silently but work with electricity and most fuels too.

The stealth bike project was launched by DARPA in 2014 and now the Silent Hawk from Logos and the Nightmare from LSA Autonomy prototypes are being shown off. Both are quiet enough to run at a noise level comparable to an indoor conversation.

It's the fuel system that's really cutting edge though. If Batman were in the market this would be the bike he would ride. In silent mode it runs on pure electricity but it can also run on fuel, nearly any fuel.

The makers of both bikes say fuels like JP-8, Jet A-1, petrol, propane and theoretically even olive oil can all power the bikes. That should mean, in a military situation, the rider can use almost anything nearby to keep going.

Alex Dzwill, an engineer behind the Silent Hawk, says: "If it’s gasoline, tell it it’s gasoline, tell it it’s something else. It will figure it out."

Even when running in fuel mode the bikes are relatively quiet at 80db, not a lot more than the 55db near-silent running then. And should the military operation mean a lithium-ion cell is damaged it won't explode and the rest of the battery will keep working thanks to an active cooling system.

Don't expect to see these bikes on the roads but perhaps once the military has them perfected, hybrid motorcycles could be an option for the public in the future.

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