Fuel-saving traffic lights make it onto the dashboard

We've all been there – trapped on a crowded bus, muttering under our breath as a bus driver who has temporarily mistaken himself for Lewis Hamilton takes a corner too fast, sending shopping, push chairs and pensioners flying everywhere.

But London bus operator Metroline is seeking to tackle the problem of overly reckless, not to mention fuel-wasting, drivers with the aid of a new device capable of instantly informing them when they are not driving smoothly enough.

The technology from US startup GreenRoad measures a vehicle's G-force as the driver accelerates, brakes and corners. It then applies algorithms to the captured data to detect if the driver is driving too aggressively and informs them of their performance immediately through red, amber and green lights on the dashboard.

As well as providing drivers with instant feedback, the data is stored and can be analysed later as part of a training or incentive programme designed to improve drivers' performance.

GreenRoad argued that the technology encourages smoother, more fuel-efficient driving styles and claims its customers have reduced fuel costs by an average of seven per cent and accidents by an average of 54 per cent as a result of the system.

Damian Rowbotham, finance director at Metroline, said that the primary motivation behind installing the technology in 100 of the company's buses was to improve safety. But he added that it was also hoping to see a reduction in fuel bills and carbon emissions.

"Fuel is very expensive at the moment and we cover 40 million miles a year so any savings we can realise are very attractive," he said. "It is too early to tell the scale of any savings and we are unlikely to realise cuts in fuel use as big as some other GreenRoad customers as our drivers have less flexibility in their routes and driving style than sales reps in company cars, but we would hope to see modest savings."