Why do automatic transmissions now get better fuel efficiency than manuals?
Not so long ago, it was common for automatic transmissions to be referred to as slushboxes, since that's how they often behaved. Rather than use a mechanical clutch, traditional automatic transmissions use a fluid coupling between the engine and the gear-sets to transmit drive torque. This provides some benefits, but isn't a perfect system.
How many gears are enough? While it seems that six-speed automatic transmissions are just now becoming the de facto standard in most circles, Mercedes-Benz has been working with seven ratios for a while now and Lexus did its German rival one better by designing its own eight-speed. Not content to sit idle while other marques earn bragging rights, Audi and BMW have recently utilized eight-speeders of their own for their latest flagship models.
Remember Zeroshift? We last wrote about them in April after we attended the SAE World Congress. At that time it was revealed that they were working on the implementation of their transmission in motorcycles, although we have not heard any more regarding when we'll see their product on a production machine. According to this article, though, the company is still finding new applications where they believe their transmission will make inroads. The latest target is heavy-duty vehicles such as buses
General Motors has decided to add production of a new six-speed automatic transmission at their Toledo, Ohio powertrain plant. The new transmission plant is designed for mid-sized front wheel drive cars like the Chevy Malibu and Saturn Aura. The new transmission is a more compact design then GM current units with the gears mounted on the same axis as the crankshaft instead of being offset. The design of the transmission will improve both performance and fuel economy. GM will be spending almost $