The BMW Z4 2.5si was a more athletic version of the BMW Z4 2.5i and was launched on the market with a model revision in January 2006. On payment of an additional charge of approximately 2,000 euros in comparison with the BMW Z4 2.5i, the customer received a more powerful engine in the BMW Z4 2.5si and a sportier response on account of the sport mode, along with a higher-quality interior with a sports leather steering wheel. The six-speed manual transmission could also be replaced by a six-speed automatic transmission with shift paddles on the steering wheel for an additional charge. This was only possible in the si models from 2006 onwards.