London mayor Boris Johnson's new diesel-electric hybrid buses were unveiled to much fanfare last week, but just days after being formally introduced to Londoners, the vehicles were making headlines for the wrong reasons.

The London Routemaster bus, which is powered by a hybrid diesel-electric engine, was travelling on the M1 and was forced to pull over because it had run out of diesel.

Before the bus set out on the London to Millbrook Testing Ground route on Monday, it had not been refuelled – causing the run to be delayed as the driver pulled over onto the hard shoulder.

A spokesperson for Transport for London said: "The bus is designed for stop-start driving, which enables the battery to be recharged automatically."

"Once the bus was refuelled it carried on its journey. We will be speaking with the operator to ensure that this does not happen again," they added.

The bus is based on HGV specialist Volvo's B5L parallel hybrid system, which boasts fuel savings of 25 per cent.

Find out more about the BP fuel card and start saving now.

Posted by Helen Wrigglesworth