BMW Z4 M40i Review: A Big Improvement, But Still No Boxster

The Z4 is a sizeable step up from its predecessor, but it doesn't have the dynamic chops to trouble the Porsche 718 Boxster S

The new BMW Z4 is a car that tricks the eyes. Thanks to its shorter overhangs and shrunken wheelbase, you’d swear it’s smaller than the old one. But it isn’t. In fact, it’s 85mm longer, but perhaps more importantly, its track has increased by 98mm at the front, and 57mm at the rear.

This gives a nice little hint as to what BMW has tried to do here, and that’s before you find out what else Munich has been up to. I’m talking about the stiffer body, the fact that it’s shed 50kg despite growing in every dimension, and the seating position, which has been shifted further forward to put you in the middle of the car.

Yes, the aim seems to have been to turn the Z4 into the driver’s car the last one wasn’t. But, you might have picked up on my very deliberate use of the word “tried” earlier on. That’s there because as a proper sports car, this two-seater doesn’t quite make the grade.

BMW - BMW Z4 M40i Review: A Big Improvement, But Still No Boxster - Features

It’s a step forward from the old one, at least, and it’s definitely capable. Damping from the standard-fit adaptive setup is on the whole excellent, with - for once - a reasonably wide range of operation. You won’t be prodding the ‘Sport’ button and wondering if it’s actually made a difference - the dampers become noticeably more firm, almost entirely ridding the Z4 of body roll while still remaining capable of ironing out dodgy bits of tarmac.

Traction levels are good, but in M40i guise, the 335bhp, 369lb ft turbo inline-six does make it reasonably easy to reach the end of them, even without switching the electronic aids off. When the limited-slip differential-equipped rear axle does start to wiggle, it’s not scary. Given a bit of space, it has the makings of a wicked drift machine.

BMW - BMW Z4 M40i Review: A Big Improvement, But Still No Boxster - Features

Going back to that engine, the 3.0-litre ‘B58’ is a muscular thing. Lag is reasonably contained, and the mid-range clout is mighty. You can rev it out if you want, but you just don’t need to. The M40i feels fast in pretty much any gear, and while BMW ruling out of a Z4 M is a pity, the range-topping model won’t leave many wanting for performance.

So far, so good, so what’s the problem? Well, there are a few things. Weight is one - the straight-six-powered Z tips the scales at 1535kg, and it’s not particularly good at masking that weight. It often feels unhappy and uncomfortable with fast changes of direction. Here’s hoping Toyota has made better use of the Z4’s ingredients in the creation of the new A90 Supra.

BMW - BMW Z4 M40i Review: A Big Improvement, But Still No Boxster - Features

Next up is the engine. It may not leave you hankering for a more impressive power figure, but it’s not so great in the noise department. It sounds surprisingly breathless even with the roof down, and I’m fairly certain there’s some additional noise being piped in through the speakers, which merely makes matters worse.

Finally, there’s the steering - as is the case with most modern sporty BMWs, it’s far too heavy in the Z4’s angrier driving modes. It doesn’t feel all that natural, either.

If driving enjoyment is your number one priority, you’ll be better served by a Porsche 718 Boxster S, which, dynamically, walks all over the poor Z4. But here’s the thing: while the bells and whistles M40i First Edition is £54,380, the Boxster S starts at nearly £55,000, and after spending a couple of minutes on the configurator you’ll almost certainly punch that figure well beyond £60k.

BMW - BMW Z4 M40i Review: A Big Improvement, But Still No Boxster - Features

The Z4, with its £49,050 starting price, seems like good value. Particularly as, if you consider what it’s like when you’re not charging around twisty roads, it has a lot of plus points. The folding roof neatly packs away in a class-leading 11 seconds, and with it back up, the Z4 is brilliantly quiet. In Comfort mode, it’s, well, comfortable, and unlike mid-range convertibles of old, there isn’t even a hint of shake from the car. There’s even a reasonable amount of boot space.

It’s a solidly-built, attractive (yes, the controversial shape has grown on me quite nicely) and capable cruiser, which will be more than sporty enough for most. And with that in mind, it might actually be worth avoiding the M40i and going for one of the inline-four-powered versions.

BMW - BMW Z4 M40i Review: A Big Improvement, But Still No Boxster - Features

Do so, and something interesting happens: the Z4 edges closer to being a sports car, if not quite making the full distance. After stepping out of the straight-six model, the 20i Sport feels almost overwhelmed with the task of providing forward momentum. You do have to thrash it to make the most out of it, but the payoff is almost no lag, and more importantly, a roadster which is much more up for being thrown around.

That’s down to the 20i being a whopping 130kg lighter than the M40i. The caveat is the body control with the Sport trim suspension isn’t anything like as resolved as the posh adaptive setup, although it is possible to spec here.

BMW - BMW Z4 M40i Review: A Big Improvement, But Still No Boxster - Features

So, which would I have? Neither, actually - the 30i, which is just 10kg heavier than the 20i but packing a more useful 254bhp from its own four-pot, looks like the natural sweet spot of the range, even though it’s expected to be the least popular model.

The Z4 is not a Boxster-beater in any guise, but next to the ageing Mercedes SLC, the flawed and pricey Jaguar F-Type and the less-than-exciting Audi TT Roadster? I think the BMW stands out as the best all-rounder.