Mercedes' first-ever production fuel-cell vehicle, the B-class F-cell, will go into limited production within weeks.
The first 200 models could be built next month and will be delivered to customers who have leased it in the US and Europe soon after.
Dr Thomas Weber, head of research and development, told Autocar at the Frankfurt show, where the car was unveiled, production will start "in several weeks".
Mercedes claims its hydrogen-electric hybrid is comparable in performance to a 2.0-litre petrol car, but its zero-emission powertrain can manage the equivalent of 86.6mpg on the combined cycle.
The electric motor produces 134bhp and 214lb ft of torque. Its range is around 250 miles and it takes three minutes to refuel the car with hydrogen. By comparison, a 1.8-litre petrol B-class (no 2.0-litre petrol model is available) produces 114bhp and 114lb ft of torque in B180 BlueEfficiency SE guise.