Responding to the NAO report, she urged the Department of Health to be careful that the efficiency drive did not lead to the NHS "shutting the door" on patients.

BBC: Why do the NHS savings matter?

In addition to the higher battery capacity clear improvements have been made to the efficiency of the drive system, resulting in a greater range.

ENGADGET: Third generation Smart Fortwo ditches Tesla powertrain, gains two wheeled cousin

The civil servant who has been leading the government's efficiency drive since the coalition came to power, Ian Watmore, left his post suddenly earlier this summer.

BBC: UK Politics