Mercedes is working on a nine-speed automatic gearbox, according to senior engineering sources.

The new ‘box will be introduced on large-capacity engines, our sources claimed.

The ‘box is said to offer huge improvements in fuel economy and CO2 emissions, but development of gearboxes with more than nine ratios is unlikely.

Mercedes engineers believe nine ratios is the maximum that is technically possible, as well as being the most that customers will be able to cope with.

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