WITH advances in technology, gone are the days when Oxford shoppers would have to battle through clouds of bus exhaust fumes.

During the past two decades, Oxford Bus Company has cut harmful emissions to clean up its fleet and improve air quality.

Now a further improvement has begun, with £5.5m invested on 19 electric hybrid double decker buses for some of the busiest routes.

Some of them went into operation this week on the X3 route from Oxford to Abingdon. Further buses will be introduced on the City 5, which runs between Oxford railway station and Blackbird Leys, in the coming weeks.

Each electric hybrid will cut nitrogen oxide by 50 per cent and carbon dioxide by over 30 per cent, compared to a normal diesel bus.

Andrew Morison, commercial manager of Oxford Bus Company, said: “This is a major investment by the company and represents a huge vote of confidence in the city’s economy — each bus costs over £300,000.

“The Government’s Green Bus Fund has contributed some of the difference between the cost of a conventional bus and an electric hybrid, in this case about £80,000 per bus.

“We are already known as the country’s greenest bus firm and the new buses boost our environmental credentials still further.

“These new buses will dramatically reduce carbon dioxide and nitrogen oxide emissions, and carbon use.”

Mr Morison said the new 72-seaters are driven by electric motors backed up by a small diesel engine. They work independently or in combination with each other, depending on driving conditions.

He added: “When the electric hybrid buses are stationary at bus stops and traffic lights, the diesel engine switches off automatically. This means the bus produces no emissions from its exhaust, as well as minimal sound.When the bus brakes the electric motors generate electricity which is stored in the batteries for use later.”

In 2011, the firm introduced in a £5m fleet of electric hybrid buses for park-and-ride routes, with 17 new double-deckers.

Stagecoach also invested £7.5m on 26 double-decker electric hybrid buses in 2010.

Hugh Jaeger, 48, a spokesman for the Oxford group of Bus Users UK, who lives in Cutteslowe, said: “These latest hybrids create 25 to 30 per cent lower emissions than low-emission diesel buses, so it is bound to improve air quality and that’s good news for everyone.”

But her warned “When these new buses pull away from the stop they are virtually silent so passengers need to watch out, particularly somewhere busy like Queen Street.”

There are 116 vehicles in the Oxford Bus Company fleet and it has no further plans for more hybrids.