CVT vs DSG transmission

The traditional manual transmission is being phased out and in 10 years time we may see only a small number of new cars on the road with manual transmissions. With more cars on the road and increasingly bad traffic jams, most drivers will choose to have an automatic transmission to make driving easier.

The most common types of automatic transmission available now are: -
- CVT or constant variable transmission
- DSG or direct shift gearbox (twin clutch transmission)
- normal automatic transmission with torque converter

CVT was originally developed by Audi in the 1980s and it was fitted into Audi cars in the early 1990s. This transmission system comprised of 2 drums that had a belt running between them. The hour glass shaped drums altered the so called "ratio" when the belt moved up or down along the drums. This constantly changing movement of the belt meant that the car would accelerate very smoothly and offered good fuel economy as the transmission system will ensure that the engine would rev lower in the RPM range. The CVT transmission was more efficient than the traditional automatics as the CVT had low transmission power loss and had an efficiency rating of up to 95%. This meant that the engine power was better used to drive the wheels. This transmission is now highly popular with Japanese car makers as they strive to improve fuel efficiency for their cars. The down side of the CVT transmission is that it is unable to handle a lot of torque and horsepower hence you will never see it being fitted into a very powerful car. It also has problems with excessive heat at high speed. Honda used the CVT transmission in their previous generation Honda City, but chose to abandon it after they were saddled with numerous warranty claims from gearbox problems. CVT transmission cars felt strange to drive as you cannot feel the gear shifts (because there are none to begin with), and the car would accelerate despite the RPM remaining the same. It had a rubber band like feel to it that many driving enthusiasts didn't like.

DSG was originally developed by VW group in 2005 and was first used in the VW Golf Gti Mk5. It is now used across all VW  models and has filtered to the Audi models as well as the Porsche models. The DSG gearbox is not actually an automatic in the traditional sense as it actually is a manual gearbox using 2 clutches. The automatic mode was added to perform self shifting like an automatic.
The DSG transmission was unique in the sense that it used 2 clutches instead of 1. The first clutch controls 1st, 3rd and 5th gear, while the second clutch controls 2nd, 4th and 6th gear. The gear shift time is so fast that it is impossible for a human to manually shift faster than the DSG transmission. The DSG gearbox is also designed in such a way that it is able to handle high horsepower and torque. The DSG transmission is currently rated as the most efficient transmission in the market with efficiency of up to 98%. DSG transmissions are split into 2 categories, wet sump and dry sump. The wet sump type which is slightly heavier are used for higher power applications while the dry sump type are used for lower power applications.

The normal automatic transmission has now taken a back seat as it is not nearly as efficient as the CVT or DSG. Normal automatic transmission only offer efficiency of up to 85%. Car manufacturers are moving to either CVT or DSG type transmissions and starting to abandon traditional automatics in the endeavor for better efficiency.