Less power but more appeal: the four-cylinder BMW Z4 is an altogether better-balanced package than its big brother...

Now that we’re well acquainted with the long-awaited rear-wheel-drive sportscar collaboration between BMW and Toyota – see our recent test of the Z4 M40i – it’s time to dial things back and see what its mellower four-cylinder stablemate is all about.
 
While the subjective sentiment around the CAR office is that the punch and snarling timbre of a BMW inline-six has few parallels, in the Z4’s case it actually may not be the best powerplant in this application. The 2,0-litre four-cylinder turbopetrol’s 145 kW may not sound like much, but allied as it is with a useful 320 N.m of torque chiming in at just 1 450 r/min, it feels deceptively punchy. Indeed, the 6,53-second 0-100 km/h sprint time it posted on our test strip managed to raise an eyebrow or two. With peak power available relatively low (4 500 r/min) in the rev range, the engine feels tractable and responds quickly to inputs from the paddle shifters. Consequently, overtaking fast-moving traffic isn’t the hope-and-pray exercise you’d expect.
 
Even the soundtrack is a pleasant surprise. Granted, it’s never going to hold a candle to the rich baritone of the six-cylinder engine and, roof-up, a portion of it is piped in via the audio system, but there’s still a pleasing thrum emanating from the tail. Nudge the drivetrain-management switch into the sport preset and there’s even the odd thrap and thud crackling from the exhaust interspersed with a spot of turbo hiss when leaning on the throttle.
 
Said sport mode has its downside, though. While it does sharpen up accelerator response and serves up more aggressive gearshift mapping, it tends to leave the transmission hanging doggedly onto gears, until blipping or flooring the pedal loosens its hold on the cogs. This occasional stubbornness is the only real scuff in the 20i’s otherwise polished and mechanically refined demeanour. Without the pulsing bass of the inline-six filtering into the cabin, it soon becomes apparent the canvas roof isn’t as well sealed from wind and road noise as you’d hope; it even had a couple of us double checking the electric windows were closed all the way.
 
Other upsides to shedding two cylinders – not to mention some of the M40i’s additional niceties, which we’ll come to a bit later – is a 125 kg reduction in overall kerb weight compared with the six-cylinder car, and the realisation of BMW’s often vaunted 50:50 front-to-rear weight distribution.
 
The 20i will never trouble the likes of the Porsche 718 Boxster or Alfa Romeo 4C in the handling stakes; in fact, that’s missing the point of this attention-grabbing roadster. This Z4 is more of a tourer which just happens to have dynamic reward woven into its fabric. Without the six-cylinder’s power taxing the chassis, it feels appreciably more poised than its bigger brother. It still has that ability to seemingly pivot about its chassis when the responsive (albeit slightly light) steering is called in to negotiate twisty roads at speed but it doesn’t succumb to the M40i’s touch of nose heaviness when things get really tight. There’s a pleasing fluidity to the way it negotiates sweeping roads and its ride, while not exemplary, is firm but not punishing and the bane of open-top motoring that’s scuttle shake is nearly abolished. Dive into corners and there’s even a degree of playfulness in the chassis, with the 20i showing a willingness to step its tail out in a controllable manner.
 
There is, however, a blot in its ledger. The M40i gave a couple of us a bit of a skrik in the form of some bump steer that occasionally lurched the car when really pushing it over rippled road surfaces, and that trait has filtered down to the four-cylinder car. Thankfully, with less power feeding those back wheels and a lighter frame which aids in settling laterally distributed weight when straightening out of a turn, this quirk of the chassis doesn’t feel as intimidating as it does in the M40i, but it is there and it’s worth being mindful of it.  



TEST SUMMARY

Lighter on its feet and with more accessible performance than the six-cylinder model, the 20i is the pick of the current Z4 litter. It’s by no means an affordable car but when viewed alongside the R1 million-plus M40i, it almost seems like a bit of a bargain. That price gap does, however, come at the cost of heated electric seats and PDC to compensate for that long nose and limited rear visibility. Even so, if you’re looking for an attention-grabbing convertible that’s capable of both composed cruising and a little bit of fun on the side, this Z4 could well fit the bill. 


See Full BMW Z4 price and specs here