The 306-horsepower, twin-turbo Z4 sDrive35i will cost a whole lot more, with a starting price of $52,475, including destination and handling. The 2008 Z4 M was a bit cheaper at $50,400 and carried more power, but the 2010 car's higher torque numbers make for an equally-quick droptop, as evidenced by its 5.1 second 0-60 time with the dual-clutch gear box.
Options abound for the Z4, and they're both expensive and confusing. Bundles include a Premium package at $3,900, or $2,800 when also ordering the $2,300 Sport package, which is $1,900 when also going premium. You can also get a performance 19-inch tire and wheel package for $1,200, but only if you purchase the sDrive35i and the Sport package. A seven-speed dual-clutch gearbox can be had on the 35i for $1,525. For complete pricing options, check out BMW's Z4 pricing sheet.
[Source: BMW Blog]