A hybrid fuel double-decker bus is being trialled in Reading less than a month after a bio-fuel fleet was axed.
Passengers have been trying out the combined fuel and electric-powered bus on the town's Premiere Route 17.
The route had previously been serviced by bio-ethanol-powered vehicles but the scheme was scrapped last month because of spiralling costs.
Fourteen buses on the town's busiest route had been running on bio-ethanol for more than a year.
Reading Buses chief executive James Freeman said: "There are several thousand hybrid buses operating successfully in the United States.
"We will be collecting customer feedback on their overall ride experience in comparison with our usual Premier Route 17 buses which is all part of our green agenda."
Last month Reading Borough Council and the board of Reading Transport, which is owned by the council, said it could no longer afford to run its bio-ethanol fleet.
Both organisations ordered an inquiry after it emerged the buses had been running on bio-fuel made from paper bi-products instead of sugar waste, as originally agreed.