the number of gears in transmissions

In the past 4 gears was the norm for car transmissions and this stayed for a long time from the 1970s to the 1980s then a gradual change took place where car transmissions moved on to have 5 gears. This stayed the same for over a decade until a few car companies decided to offer 6 gears. This was limited to some top end luxury cars such as BMW, Mercedes and Porsche.

Since the mid 2000 where the oil price shot up every car maker was rushing to introduce cars that offer better fuel economy and seeing that it was difficult to squeeze more efficiency from an engine the next best route was to improve the transmission by offering more gears. It was proven that with more gears and lower gearing at cruising speed the engine would rev lower thus saving fuel. This concept did make sense but it was somehow got carried away with car maker nows push up to 10 gears in their transmission system. BMW started using their 8 speed automatic in the F10 5 series and F30 3 series, then came Mercedes with their 9 speed automatic in the S and E Class models. Ford and Honda and Hyundai took one step further by introducing 10 gears.

Honda was previously focused on using the CVT system but it was not well received and had problems. Honda filed for patent for their triple clutch 10 speed transmission making it the first in the world triple clutch 10 speed. Ford and Hyundai were using conventional automatic transmission but adding the gears to make up 10. With this number of gears the transmission would have to be automatic as it would not be practical to swap gears manually. Porsche pushed the maximum number of gears for manual transmission to 7 and this was getting troublesome. With so many gears the driver will be spending too much time holding onto the gear level changing gears all the time. It didn't make practical sense.

Transmission systems with high number of gears have been around for a long time but those are installed in trucks and buses where the truck or bus has to lug heavy weight and being diesel the rev band is very short. the bus or truck had to be in the power band to be able to lug the heavy payload.

On the flip side electric cars have no gears and is able to run without using a conventional transmission. It will be interesting to see how far transmission technology will change in the near future.