THE hope was a greener and quieter fleet of buses for crowded Sydney streets.
But a trial of hybrid buses - using an electric motor to power through stop-start inner-city runs - has been declared a failure.
When the former transport minister, Labor's John Robertson, announced the trial service to operate from Leichhardt depot in 2010, he said two models of part electricity-powered buses would be considered. One never made it to the trial after the company developing it pulled out.
The bus trialled ran through the inner west and the CBD through late 2011 and early 2012. According to drivers and passengers, it handled well, offered a smooth ride and was quieter than diesel-powered vehicles.
Its cost, about $140,000 more than a comparable diesel bus, counted against it. So did the fact it generated slightly more greenhouse gas emissions.
''Substantial improvement of the current hybrid offerings is required if this promising technology is to compete directly with contemporary diesel bus offerings,'' the final report on the trial, by Rare Consulting, said.
The report said the reliability of the technology, the cost of the buses and the level of after-sales support needed to be improved.
A spokeswoman confirmed Transport for NSW would not be buying hybrid vehicles, increasingly being used in Europe.
"Hybrid technology is a work in progress and when improvements in technology, reliability and costs are made in the future, it will certainly be worth considering again," she said.