As we reported a few says ago, Mercedes has launched a new variant of the E-Class, powered by the 350 BlueTEC engine, that features a new 9-speed automatic transmission. Now the German car maker has released more details about the new unit to try and explain why it is a good idea.

There is nothing fundamentally wrong with a 9-speed transmission. But it’s complicated. And everybody knows that simple things work better. It’s like those razors that have many blades. At first there were only two blades, and they worked pretty well. Then somebody did one with three blades, then four, and five. And they are all rubbish.

In any case, the new 9-speed ‘box is mainly developed for better fuel efficiency. It doesn’t change the performance of the E350 model at all, but it does make it slightly more economical, especially in the town. It is a conventional automatic with torque-convertor based on the old 7G-TRONIC unit, with broad ratio spread of 9.15 for gears one to nine. A 9-speed transmission is a busy little thing, constantly changing up and down – especially with such ratios (see below).

But Mercedes guarantees that the shifting has been optimized in this system and they are barely perceptible. Improved comfort is mentioned as the other advantage of the new gearbox besides improved fuel efficiency.

So let’s talk some numbers and see how the world’s first production 9-speeder does in the real world. In the E 350 BlueTEC, which is available as Saloon and Estate models and comes fitted with the new 9G-TRONIC as standard, the 185 kW (252 hp) V6 diesel engine has an average NEDC fuel consumption of 5.3 litres of diesel per 100 kilometres (Estate: 5.5 l/100 km), corresponding to CO₂ emissions of 138 g/km (Estate: 144 g/km).

Prices for the Mercedes E350 BT equipped with the 9-speed transmission start from 54,710 Euros for the saloon, and 57,923 Euros for the Estate version.

Power transmission