The BMW Z4 sDrive35is is the ultimate convertible sportscar under $150,000.

Model Tested:

• 2010 BMW Z4 sDrive35is; 3.0 litre, six cylinder, twin-turbo petrol; seven speed dual-clutch  transmission; two door sportscar: $129,900

CarAdvice Rating:

It’s not often that one would consider working on their birthday, but I made an exception when it came to picking up the ultimate Z4. Perhaps it was a birthday present in disguise.

You see, the BMW Z4 has been fighting hard against the Audi TT, Porsche Boxster and to a lesser extent, even the Nissan 370Z. In September this year BMW Australia sold just 16 Z4s. In total the German company is unlikely to sell over 300 units over the course of the whole year. In fact, the number of BMW Z4 sDrive35is convertibles heading to Australia are limited to say the least.

This is a good thing because if you’ve got about $130,000 to spend on a über-unique convertible sports car, put this right up the top of your list.

BMW has brought out the sDrive35is as a way of combating the Audi TT-RS and Porsche’s Boxster S. It’s hard to understand why the M badge hasn’t been applied because the sDrive35is has 250kW and 500Nm of torque (almost the same power as the previous Z4M and more torque). That means a 0-100km/h time of just 4.8 seconds (same as the manual M3).

Purists may be slightly disappointed knowing that it’s not available with a manual gearbox, but then again the seven-speed sports automatic transmission with double clutch operation is perhaps one of the best gearboxes in the business (used in the BMW M3), so there is little to be concerned about.

The press car was red, which is ideal for a convertible, although the Z4 does look good in pretty much any colour (even if the mirrors are a little odd). The paperwork was signed, the key was handed over and it was time to see what all the fuss was about.

Unlike some Australian motoring journalist that are simply far too old to enjoy roof-down sports convertible driving, I hesitated for about half-a-second before turning the Z4 sDrive35is into a proper convertible (via a button on the console). The roof operation takes 20 seconds.

If you’ve never sat in a Z4, you will quickly notice that the cabin is a little bit like the rest of the BMW model range, from the iDrive controls to the LCD screen and cd player, the Z4′s interior may be adequate for the standard models but the sDrive35is really does beg for a little more character, even if it’s just some colour coded stitching.

Don’t get me wrong, BMW has added aluminum carbon interior trim finisher as well as an M leather steering wheel but it can do with more personality.

Press the start button and the Z4 sDrive35is comes to life with a little growl. You’ll be happy to know this is the most powerful factory implementation of BMW’s outgoing twin-turbo 3.0-litre six-cylinder engine (which has won numerous engine of the year awards). The engine is being replaced by a single-turbo twin-scroll setup (already seen in the 5 Series) in the near future.

You can either just put the car in D or attempt to use the counter-intuitive steering-wheel paddles. It’s such a shame that BMW hasn’t updated the Z4 sDrive35is’ steering wheel paddles to match the ones found in the new M3.

As it stands now, the paddles on both sides are able to change up and down, making gearshifts just that little bit more confusing. Traditionally the left paddle is down and the right paddle is up (as with the new M3). It may seem like a big deal at first, but give it a few days and you get pretty used to it and by week’s end it’s a nonissue (preferably though, the left-down right-up setup is still more logical).

With the roof stored away, the Z4 sDrive35is is just like any other Z4 around town. Leave it in D with ‘Normal’ mode selected and it can sleep all day in traffic, the gear changes are extra-smooth and despite its performance credentials you can easily drive it to work everyday in peak-hour traffic without feeling uncomfortable.

The real fun, however, starts when you engage Sports + mode and launch control. It works a little like this: once the engine has warmed up you simply pick Sports +, put the gearshift into manual mode, put your left foot on the brake pedal and your right foot on the accelerator. All of a sudden a checkered-flag will show up in the instrument cluster display and the engine will hold its revs at about 4,000rpm, ready to launch you in to space.

The millisecond you let go of the brake pedal the Z4′s 250kW and 500Nm of torque will physically smack you back into your seat as it begins tearing up the tarmac on its way to 100km/h in under five seconds. Having tried this… oh, I don’t know, a ‘few’ times, I can tell you that launch control is actually rather violent (read: extremely fun), which makes it stupidly addictive. The Z4 does tend to want to slide a little when launched, it needs some guidance otherwise you may end up in the bushes.

More importantly the local constabulary wouldn’t be all that happy with you trying this at a set of lights, so a race track should be frequented if you plan on buying this beast. Nonetheless, if ever you do happen to come next to a Porsche Boxster S at a set of lights you will have no issues beating it to 100km/h by a good 0.5 of a second. It’s fair to point out that the Audi TT-RS is 0.2 seconds quicker to 100km/h.

Around tight corners the Z4 is a little twitchy. Having driven the BMW 335i Convertible the week before, the Z4 felt a little more nervous which in some people’s books is another word for fun. In normal mode it’s too soft for sporty driving but in Sport and Sport + mode the adaptive M suspension can literally lower the Z4 by up to 10millimetres, which means a hard, firm and sporty ride.

The steering can do with a little more feedback as it does feel a little over-assisted. Furthermore the steering to wheel movement ratio is so damn precise that you can make yourself sick with the car’s rapid cornering ability.

BMW says the damper stiffness is managed by a system that is capable of adjusting on the fly. For example the second the front wheels drive over a bad patch of road (hole, bump) the rear dampers have already adjusted in anticipation.

Take it up a twisty mountain range and the Z4 sDrive35is really shines. Accelerate hard towards a corner, heavy on the brakes upon approach, attempt to gear down, realise that you actually went a gear up instead, curse BMW’s steering-wheel mounted paddles, gear down twice, point the front wheels in the right direction, plant your right foot flat to the floor, engage hyper drive – smile uncontrollably. It’s hard to get bored of this.

The rear-wheels are not as well planted as an M3 and the Z4 does try to kill you once in a while, but then again that’s why it’s the ideal convertible sportscar. It’s fun! And in this day and age, fun and powerful cars are far and few in between.

Driving it around town, the performance-orientated Z4 certainly turns heads. Even parked on the side of a busy road the sDrive35is is beautiful in its own way (you can argue otherwise, I am sure). It’s distinguishable from the lesser Z4s by its standard 18” light alloy wheels in “Star-Spoke” styling, M sports kit and sDrive35is badging. BMW has also redesigned the car’s exhaust system for a unique and glorious sound.

As with all BMW cars, safety is top-notch and the Z4 gets driver and passenger front and side airbags as well as a whole bunch of active safety features (that I shall not bore you with).

Overall, for $129,900 you can either buy this or a Porsche Boxster S (or spend a little more on the TT-RS). The Boxster has less power, is slower and getting replaced soon, however the Audi TT-RS does represent a worthy competitor.

If it was my $129,900, I would stick with the Z4 sDrive35is simply because I can’t get over how much engagement is required to get the best out of it. For me, having to actually ‘drive’ the Z4 to go really fast easily outweighs its few negatives.

For more information and specifications: BMW Z4 Range.