Abstract Market trends clearly demonstrate the ongoing worldwide acceptance and success of modern automatic transmission solutions (AT, CVT, DCT) in both passenger cars and light trucks. This success is based on the further development of the driving comfort, shifting dynamics and - most important - the fuel consumption reduction modern automatic transmission systems offer. First, key driveline parameters such as overall spread and number of ratio's are to be discussed. The optimum spread for the fuel efficiency is in the range of about 8 to 9 and can typically be achieved by 8 to 10-speed transmissions. This is because modern gasoline or diesel- engines have a rather flat characteristic fuel map. Therefore the inner efficiency of the future transmissions becomes increasingly important. The second generation of ZF's 8HP automatic transmission is now introduced which was designed to be used in combination with the latest engine technology that most notably features both downsizing and down speeding. The second generation 8HP features an overall increase in spread with optimized components and new functions. Further options to reduce fuel consumption, packaging, and weight even further are described. A revised oil supply, the use of dog clutches and additional overall spread which makes this possible. The production figures of ZF's Saarbrücken plant have been increased dramatically the recent years. Some innovations in manufacturing are described, which also made this possible. Introduction During the past decades the technology of automatic transmissions has been steadily increased. Shift comfort and dynamics and as well as drive performance were improved, while at the same time the fuel consumption and CO2-emission were reduced.These improvements were reached with different transmission concepts. In Figure 1 planetary transmissions together with CVTs and DCTs can be seen. Starting from the former 3 to 6-speed AT's, meanwhile the 8 or even first 9-speed AT's are now the state of the art in the market. Parallel to that, the various generations of CVT's were introduced. The newest transmission technology introduced in vehicles more recently are Double-clutch transmissions, with 6 or 7 speeds and now 8 or even more speeds have been announced to be in development. Fig.1. Technological Trend of Automatic Transmissions However, to meet future fuel economy regulations, the transmission technologies alone are not capable to reduce fleet consumptions to the announced limits. Therefore, in future we will see an increasing amount of hybrid systems. Driveline Parameters The well-known ZF 8-speed AT is a very fuel efficient and cost-effective transmission system. Its key parameters are shown in Figure 2. What could be done to get even more fuel economy from the transmission in combination with future combustion engines (more spread? more speeds?) and keep the costs of the transmission?Advancement in NVH- and Fuel-Saving Transmission and Driveline Technologies2015-01-1087 Published 04/14/2015 Juergen Greiner, Martin Grumbach, Albert Dick, and Christoph Sasse ZF Friedrichshafen AG CITATION: Greiner, J., Grumbach, M., Dick, A., and Sasse, C., "Advancement in NVH- and Fuel-Saving Transmission and Driveline Technologies," SAE Technical Paper 2015-01-1087, 2015, doi:10.4271/2015-01-1087. Copyright © 2015 SAE InternationalDownloaded from SAE International by Tsinghua University, Friday, June 08, 2018Fig 2. Parameters of ZF 8HP (8-speed Automatic transmission) A calculation was carried out, to show the effect of overall gear- spread and number of gears with respect to the fuel economy. As can be seen in Figure 3, the increase of the overall gear spread indicates a fuel saving potential up to a gear-spread of 9. Increased spread does not show additional potential. This ideal range of gear-spreads would typically be achieved by 9 or 10 speeds transmissions, but also 8-speed AT's can be adapted to be able to deliver that