Despite tasking the new BMW Z4 with a broader remit that encompasses the softer side of roadster duties, BMW has not overlooked performance.

The range-starting sDrive20i and the sDrive28i are both excellent engines that complement the Z4 beautifully. They deliver a blend of pace and economy that BMW seems to be able to achieve consistently better than its rivals.

A roadster should, regardless of your speed, make you feel good about driving it, and somehow the Z4 misses that mark

A Z4 sDrive28i is not only capable of 0-60mph in 5.7 seconds, it can also return 41.5mpg and emits only 159g/km. Our experience of the engine shows it be effectively lag-free and characterful also.

Fitted with the optional seven-speed, dual-clutch gearbox, the sDrive35i sprints from rest to 60mph in just 5.1sec, matching the time we recorded for the outgoing Z4 M Coupé. Although the M car is quicker to 100mph (by only 0.4sec), the new Z4 has the advantage over the more relevant 30-70mph increment, needing only 4.3sec.

Underpinning that impressive performance is the now-familiar twin-turbo straight six, unchanged from its applications in the 1 Series and 3 Series. It may not have quite the same zingy top end as BMW’s naturally aspirated sixes, but as an engine to tackle the variety of conditions our congested roads present, it is difficult to fault. The efficiency of the DCT gearbox also contributes to the performance potential.

At 335bhp, the 35iS has 33bhp more than the regular 35i. There are some visual tweaks but chassis changes are limited. Beyond a freer-flowing exhaust, there are no mechanical changes to the 35iS's motor over the 35i's. That's okay, because the turbocharged 3.0-litre six was already a stonker.

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The way the 35iS picks up and pulls cleanly through its rev range is world-class, and now it comes with the kind of exhaust rasp that's been missing from the line-up since the demise of the old M3. Economy and emissions are on a par with the regular 35i, too.