The Z4 sDrive35is is based on the currently range-topping sDrive35i and uses the same three-litre six-cylinder twin turbo petrol engine. That engine, however, has been uprated and now produces 340bhp rather than the standard 306bhp, while maximum torque has been increased from 295lb/ft to 332lb/ft in normal circumstances and 369lb/ft for brief periods of hard acceleration.