BMW 4-Cylinder Engines Return to US in 2011 in the Z4 sDrive28i Like the company's latest TwinPower Turbo 3.0-liter turbo inline-6, the new 2.0-liter engine combines high pressure direct-injection and BMW's VALVETRONIC intake control (hence the name: TwinPower) with a forced induction system consisting of a single twin-scroll turbocharger. With 240 horsepower and 260 lb-ft of torque, it offers more power and torque than BMW's normally aspirated 3.0-liter inline-6 that it replaces in the Z4 sDrive30i.