M Sport trim brings an even more aggressive look, although you’re not getting a whole lot more than added style for your money with a sharper-looking body kit, gloss black accents and an M Sport leather steering wheel being the main equipment upgrades. Yes, you also get firmer M Sport suspension and beefier M Sport brakes (on the sDrive30i), but these don't do a lot to make the driving experience more thrilling. 

The same engine that you get in the sDrive 20i but with a much healthier 255bhp. It's quick, too, getting from 0-62mph in just 5.3 seconds. However, it suffers from the same monotonous engine note as the base sDrive 20i and the gearbox is just as sluggish. Therefore, we'd advise you by the cheaper sDrive 20i if you want a Z4 to cruise about in, while those who want something that sounds good should look at the full-fat M40i.