• All-petrol line-up for the Z4
• Each one has its strengths
• You don’t need the fastest to get the best

Petrol engines

Two petrol engines are available in the Z4. There’s a 2.0-litre unit (197hp, 0-62mph 6.6 seconds) and a powerful 340hp 3.0-litre range-topper with a sub-five second 0-62mph time. All models come as standard with an eight-speed automatic transmission with manual and sports modes. A six-speed manual is optional on the 3.0-litre as part of the Handschalter Pack.

We think the 20i could be the pick of the range. Just shy of 200hp is more than enough in a car of this size, and it feels quick to respond when you put your foot down. The power delivery is smooth but responsive, and it even sounds good thanks to a sportier note coming from the exhausts.

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The M40i’s engine is impressive, too. BMW has worked to make it more responsive in the Z4 compared with other models and that suits its sports car character well. There’s plenty of power, but at times it can feel too much on a tight and twisty road – you probably wouldn’t be far behind in the sDrive20i thanks to that car’s lighter weight and equally sharp responses.

And while the six-cylinder sounds good, the overall feel isn’t one that would suggest it’s worth the extra cash over the entry-level car that feels more of a lightweight sports car than this one. In fact, the M40i feels very nice as a relaxed cruiser thanks to its silky smooth engine, but then that almost negates the point of it being the performance option.

What’s it like to drive?

• Sharper handling on lower-output car
• M40i can feel a little heavy in corners
• Both models are nicely balanced though

While the sDrive 20i is the entry-level model in terms of power output, it feels far from the poor relation. Quite the opposite, in fact. With just shy of 200hp and the lowest kerbweight of the Z4 range, it feels lively and agile on a twisty road. The responses are sharp from the steering without being twitchy, it’s keen to turn into corners and being able to tweak the driving modes means you can personalise the way it feels according to your preferences.

There are a few too many of these, however. With a choice of Eco Pro, Comfort, Sport and Sport Plus (plus Adaptive if adaptive dampers are fitted) there are already several options. However, when you select these, you can then choose Individual versions of all of these, so it can take a little while to find the ideal setting.

In Comfort, the Z4 is an excellent cruiser with a composed ride and relaxed feel thanks to light-yet-communicative steering and a refined engine. Flick it into Sport, however, and the gearbox, engine and steering become sharper, and some very pleasing cracks and pops come from the fruity-sounding exhaust. It feels every inch the sports car and sounds great.

Add to that the sharp responses and it’s more engaging than you might expect. However there can be a slightly dull feel to the steering that you simply don’t get in the pin-sharp Porsche. Blame the long nose and the roadster seating position.

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Despite being a convertible, the Z4’s structure feels very rigid and adds to the composure you feel when driving on a twisty road as well – it feels far superior to the previous model, but again can’t quite match the Porsche Boxster for outright thrills and engagement.

The firm suspension is absorbent enough to deal with mid-corner bumps and camber with ease and lets the Z4 feel hunkered down when the mood suits – it’s only on really badly surfaced roads that will have you wanting to ease off the pace a little.

The M40i comes with a powerful 340hp six-cylinder engine, and is also fitted with some extra mechanical goodies the lower four-cylinder model doesn’t come with. In particular, it gets electronically controlled shock absorbers, which vary their stiffness on the go, and an electronically controlled differential – something similar to the high-performance BMW M5. 

Like the other models, in Comfort mode it’s very forgiving, while in Sport and Sport Plus everything becomes much sharper – including the weighted up steering that’s fast to react. The stiffer suspension it brings does highlight a few creaks in the body’s structure, and can’t make the M40i feel as agile as its little brother, even with the Handschalter Pack’s suspension tweaks.

There’s very little body movement as you go into a corner and the car adjusts itself, however it can also be surprisingly tail-happy, although never unpredictably so. We’d stick to the standard eight-speed automatic as it suits the car’s laid-back bruiser attitude better. Besides, the six-speed manual feels a bit rubbery and notchy, while top gear feels a bit too short for relaxed cruising, leaving the engine revving higher than you’d like.