1 Results from the Microcab fuel cell vehicle demonstration at the University of Birmingham Iain Staffell Centre for Hydrogen & Fuel Cell Research, Chemical Engineering, University of Birmingham, UK. staffell@gmail.com / +44 (0)7940 329303. Originally published in the International Journal of Electric and Hybrid Vehicles, Inderscience Publishers. http://dx.doi.org/10.1504/IJEHV.2011.040473 Abstract The UKǯs first fleet of hydrogen fuel cell vehicles – the Microcab H4 series – has been demonstrated at the University of Birmingham for 21 months. The five prototypes have been used interchangeably as four-seat urban taxis and light goods vehicles around campus, accumulating over 4,000 km on the campus road network and being filled with 68 kg of hydrogen. The performance and efficiency of these vehicles have been monitored in-situ throughout the trial, using custom-built data loggers for the fuel cell and other power-train components. This paper presents the key findings relating to the power-train performance and efficiency. While the peak tank- to-wheel efficiency was 27%, the Microcabs were found on average to be 18% efficient at converting hydrogen into tractive power. The causes of this loss in efficiency are analysed and discussed, and show that improving the control and interaction of the individual components would result in substantially improved vehicle performance.