13 Oct 05
Turn the ignition key and very little seems to happen, just a gentle whir from the air compressor forcing atmospheric oxygen into the fuel cell stack. But you can't start driving a fuel cell car straightaway; you have to let the system prime itself with hydrogen and oxygen before it can start the chemical reaction. After 30 seconds' wait, an indicator on the dash tells me we're ready to go - as does the gentle puff of steam from the exhaust pipe.
I slot the auto box into drive, release the handbrake and feed my way into heavy London traffic. From standstill, the A-Class is plenty quick, 30mph coming up in around five seconds. Electric motors are unique in the way they deliver all of their available torque (156lb ft in the A-Class's case) straightaway, instead of gradually building up to the peak before plateauing, then falling, as with regular petrol or diesel engines.
Feeding the A-Class through traffic is a cinch thanks to that instant torque, allowing last-minute lane changes without annoying short-tempered London taxi drivers and white van men too much. However, stretching the A-Class further on the open road shows that although it's quick to 30mph, it takes a lot longer to reach the benchmark speed of 60mph - over 15 seconds in total. The electric motor is only good for 87bhp, meaning that the extra 400kg of the fuel cell system's mechanicals limits acceleration. Top speed is also limited by the laws of physics (rather than electronics) to 87mph.
