The hobby known as tunnel running attracts hundreds of drivers keen to show off their modified cars.

BBC: East London police to monitor tunnel running events

Its system uses modified railway cars on a specially built track.

ECONOMIST: Energy storage

Likewise, BMW withdrew its own test fleet of 100 cars with internal-combustion engines modified to run on hydrogen.

ECONOMIST: Tech.view: Hydrogen tries again | The

Where other car-customizers modified Chevys and Fords, Roth built wholly new, surrealist cars.

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