6-speed gearbox
Advantages:
*Improved fuel economy due to wider gear ratio spread
* Smoother gear shifting due to additional steps
* Better acceleration at higher speeds thanks to additional gear stages
* Reduced noise levels when driving on highways
* Increased transmission life due to more even load distribution between gear stages
Flaws:
*Higher cost (compared to 4-speed gearbox)
* More thorough maintenance required (additional fluids and filters)
*More complex design which may result in more expensive repairs