Just as much performance, far superior economy.
We've already seen Autocar conduct a high-performance sedan battle between the BMW M3 and Alpina D3, with little to separate the two. Now the British publication wants to see just how well the D4 BiTurbo performs. Powered by a 3.0-liter twin-turbo six-cylinder diesel engine rated at 350 hp and 516 lb-ft of torque, with plenty of refinement, a six-speed auto, and a properly sorted chassis, Steve Sutcliffe is of the opinion the Alpina D4 is perhaps the best performance diesel on the market.
Given the choice between this and the M4, the everyday usability and impressive fuel economy makes the Alpina D4 the hands-down winner.