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When it comes to sheer driving pleasure, in an open top sports car, what's the most important facet? Is it agility? Is it out-and-out performance? Is it ease of accessibility - how fast you can raise and lower the roof?
Until today, you didn't have much choice when it came to the BMW Z4 Roadster.
You either had a 2.5-litre six cylinder version with not a lot of grunt, or a 3-litre which gave much, more.
Either way, the cars were not really agile in the way that, say, a Mazda MX5 is truly agile.
Nor in many respects, was their styling as up-to-date as BMW would have you think. The sides may have been flame grilled (is that the right term?) by Chris Bangle and his team, but there was something missing in the detailing, especially inside the car.
Enter, then, the new range of BMW Z4s, starting out with a 2-litre four-cylinder version that pushes close to the performance of the old 2.5-litre six while delivering a delightful ride and handling package that will satisfy owners of the benchmark MX5.
Add in a new 2.5si which gives performance close to the old 3 litre's, but thanks to a lighter engine retains much of the agility of the 2-litre while delivering better grunt that comes close to the old 3-litre.
Then, on top of the tree (that is, until the M versions with their 3.2-litre M3 motors get here in a few weeks' time), you find the new 3.0si, dashing to 100 km/h in almost a second less than the old one.
Still heavy at the front, but much less so thanks to a weight-shedding exercise by using magnesium as well as aluminium in the engine block and some components.
And, of course, you can enhance the package by dipping into the BMW Individual parts bin.
Styling
The front end of the Z4 was always, to me, a bit heavy. BMW has lightened it up a lot now, in this mid-term refresher, by widening and enlarging the front airdam, and at the same time slotting in new foglamps which follow the shape of the opening to make them more integrated than the old round ones were.
One-piece projector headlamp units are now fitted, with bi-Xenon standard on the 3-litre, optional on the rest. And the lights don't switch on and off to dip - they're all on at once, with a mechanical shutter changing them from dip to high beam.
Much faster
The car's position lights are formed by two light conductor rings, into line with in other models in the BMW range.
Not much changes on the sides - there are reflective markers on the front wheel arches - and a new range of model-specific alloy wheels is fitted.
Then we move to the back of the car, where the tail-lights, again to my mind a weak styling point in the old car, are upgraded.
Instead of round items we now get a fully integrated "teardrop" shape that features the "light conductors" seen on more expensive BMW models, the whole giving the backend more horizontal lines for a wider, lower, and more muscular appearance.
The interior
The dashboard of the Z4, as I remember it, was previously bleak and uninteresting.
Now, though, there's a choice of dashboard trim finishes that broaden its appeal.
In addition the switchgear has been given a better feel by adding rubber inserts which prevent fingers slipping.
The layout remains unchanged, though, with the 2-litre in particular impressing with its simplicity and ease of operation of the controls.
One of the things the new cars retain is the super-quick folding soft-top - down in just 10 seconds, matching the previously fastest "stripper", the Honda S2000, and much quicker than any of the folding tin-tops on the market.
Just press a button and it all happens electrically, with no need to lock or unlock anything.
The hood is triple-layer, to keep out heat (or cold) and wind noise. When it's folded normally you still have 240 litres of boot space, though this can be enlarged a further 20 litres when you really need it - though you'll not then be able to lower the hood.
BMW says it will hold two sets of golf clubs
The engines
The 2-litre four-cylinder power unit featured in the BMW Z4 Roadster 2.0i develops 110 kW at 6 200 r/min and maximum torque of 200 NM at 3 600 r/min.
Acceleration to 100 km/h takes just 8.2 seconds, exactly the same time as the fast sprint from 80-100 km/h in fourth gear, while top speed is 220 km/h.
With BMW's VALVETRONIC and dual-VANOS management systems it's also quite very fuel-efficient, averaging 7.5 litres/100 km.
The BMW Z4 Roadster 2.5si produces 160 kW with peak torque of 250 Nm in a broad band from 2 900 to 4 250 r/min, accelerating the Z4 Roadster 2.5si from 0-100 km/h in 6.5 seconds - less than a second slower than the old 3-litre.
Top speed is 240 km/h and average fuel consumption is 8.4 litres/100 km.
The new 3-litre straight-six in the BMW Z4 Roadster 3.0si is said to be the most innovative engine in its class, with a high output per litre, a very good power-to-weight ratio, and low specific fuel consumption.
Maximum output is 195 kW at 6 600 r/min, maximum engine speed is 7 000 r/min, and the engine develops its peak torque of 315 Nm at 2 750 r/min.
The Z4 Roadster 3.0si accelerates from 0 to 100 km/h in 5.7 seconds, with top speed limited electronically to 250 km/h. Claimed average fuel consumption is 8.6 litres/100 km.
In addition all Z4 models now come with 6-speed gearboxes, manual only on the 2-litre, or optionally full Steptronic autos (not SMG - that's no longer available) with paddle changers on the steering wheel on the sixes.
The ratios are nice and close, and the change is as slippery as the proverbial hot knife through butter.
On the road
The Z4 has gained highest points to date for an open-top car in Euro NCAP testing in terms of its body rigidity, and this shows on the road.
There's absolutely NO body shake under any circumstances (and we drove on the many potholded roads of the ZwaZulu Natal Midlands to prove it) while the stiff chassis enables the suspension to do its work without having to second-guess what the body is doing.
The 2.0i is undoubtedly the star of the show here.
The steering is very light and crisp, with a lovely positive feel, and this can be enhanced further by pushing the "Sport" button on the centre console.
This speeds up steering responses further and also livens up the throttle responses.
The 50-50 weight distribution puts the moment of inertia right under your bum, which means you can literally ?feel? what the car is doing, or going to do, at all times.
I hit quite a few dips at high speeds, in mid-corner, but not one managed to unsettle the car's backend.
The 3-litre isn't anywhere near as crisp or satisfying in terms of its handling, though its performance leaves little to the imagination.
We know the M Roadster will have even more power, but quite honestly, we found the 3-litre has enough for an open top car.
After all, faster than 120 km/h, and you're screaming at the top of your voice to your passenger while your hair feels as if its starting the tangle of all tangles.
The Z4 comes equipped with diffusers behind the seats, built-in to the rollover hoops, but they're not much good at high speed.
So we get to the 2.5si.
Not as agile as the 2.0i, but better than the 3.0si.
If you're forced to choose, for me, the one I'd prefer.
New DSC settings
One of the reasons why the new Z4s are more thrilling than the old ones - all of the above included - is that the cars now have new Dynamic Stability Control settings.
These allow you to explore the car's handling to a higher degree than before without interfering. They also include Hill Start Assistance and Dry Braking, on all models.
A new feature is the 17 inch brake system on the Z4 Roadster 3.0si. We used this in anger a couple of times, and it is REALLY good.
As with all BMWs you can mix and match components such as audio systems, satellite navigation and so on to suit your pocket.
Or you can Individualise.
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