BMW 420d Convertible 2014 review

Folding metal hardtops haven't doomed the coupe to the history books or sounded the knell of the cloth-topped convertible, but if versatility counts in your next four-wheel hair-dryer, the BMW 4 Series cabrio should be on your list.

VALUE

Sneaking in at just under $90,000, the 420d Convertible - adding the no-cost extras of the Luxury Line - comes at a $17,000 premium over the equivalent coupe.

Beyond the folding metal roof, there's plenty of cool gear - 18-inch alloys, leather-wrapped steering wheel with audio and phone controls, cruise control with braking function, paddle shifters for the eight-speed auto, dual-zone climate control with rear vents, LED interior lights, powered and heated front sports seats, split-fold rear seats and detachable wind deflector.

Techno-tricks are covered by the wide-screen colour monitor for the satnav that also controls the drivetrain and the six-speaker audio, which in turn has Bluetooth and USB input and a 20Gb hard drive for storing your favourite open-air cruising music.

The Luxury Line adds flashes of chrome and aluminium, distinctive alloys and ambient light offerings. The $1840 for metallic paint is a bit rich.

DESIGN 

Nobody will pick the 4 Series - formerly known as a 3 Series Coupe or Convertible - as anything but a BMW. With its new badge, the droptop is 26mm longer and 43mm wider and a smidgen lower to the ground.

It also adds 50mm to the wheelbase and claims 40 per cent improvement in rigidity, a claim verified by the driving experience that yielded no creaking or groaning.

Plenty has gone on under the skin. The hardtop, which takes 20 seconds to fold at up to 18km/h, has been finessed to further reduce the cabin noise and the slippery shape cuts wind noise and buffeting with the roof down.

Cabin space for the four-seater is also pretty good, more so in the front for adults than in the back. All will need to pack light if a roofless roadtrip is on the cards. When the roof is up, bootspace is 370L, which isn't cavernous (the coupe has 445L). Folding the metal roof leaves 220L - all of 20L more than in the outgoing 3 Series Convertible.

ENGINE / TRANSMISSION

For an entry-level model the 420d doesn't come in underpowered. The diesel soundtrack won't have the hairs on the back of the neck standing but the turbo diesel (135kW/380Nm) can get the rear tyres chirping.

This torquey job will get to 100km/h in 8.2 seconds (just under a second slower than the 225kg lighter coupe) and slips through the eight ratios to return a claimed 5.0L/100km, abetted by stop-start engine cutout, brake energy recovery and BMW's Eco Pro mode. Our overall test figure was 7.1L.

SAFETY 

Expect five stars, as per the 3 Series two-door. The propeller badge brings a long list of safety gear, from four airbags to active rollover protection - two hidden rollover bars extend in less than 200 milliseconds.

There are bi-xenon headlights, run-flat tyres, auto-dimming mirror, LED fog lights and tail-lights, parking sensors front and rear, reversing camera and rain-sensing wipers, which when activated will put the lights on.

DRIVING 

BMW's flatter, broader styling direction is not for everyone but it makes the cabrio more purposeful in its stance.

With the roof keeping solar damage and riffraff at bay, the journey is quiet - apart from what seems a distant diesel chug - and comfortable, at least until the run-flats disagree with a road-rut. Ride quality - from the run-flat rubber and the suspension - is slowly getting better.

The auto slips slickly between gears to reach cruising speed and once up and rolling the engine noise is largely gone. Judicious use of the throttle keeps the engine in its stride, ahead of the traffic and thrifty on fuel.

Access to the rear is achieved without seat belt entanglements - the front seats have self-contained seat belts (as in early Range Rovers), a good setup to get rear passengers in and out. The rear bench's backrest is a little too upright but there is adequate room (and windows with switches) for occupants.

The rear seat backs can fold down for more cargo. Tether straps slip through via a zipper arrangement for child seat anchors. Once in, the rug-rats love a bit of open air-running Wind buffeting isn't extreme either, even at highway speeds although there is a windblocker for two-up trips.