The "d" stands for diesel. But nevermind that for a sec. It produces more off-the-line torque than the petrol-engined M3, with a huge powerband of 1,500 to 5,000 rpm. It averages about 43.5 mpg, and one can wring 605 miles from a single tank. It keeps pulling to 150 mph. It's a legit four-seater coupe with a functional, pleasant interior. It feels fast, balanced, and precise. And back to that pesky "d": it means it's a European model only.