Car reviews - BMW - 4 Series - Cabriolet range
Big fuel use savings despite extra under-bonnet performance, sharper dynamics, metal roof can now stow on the move, clever boot loading system, added benefit of pillarless coupe design with roof in place.
Room for improvement
Price rise by default from limited three-model line-up, only-for-Australia child restraint system reduces some practicality and comfort.
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17 Nov 2014
By BARRY PARK
For now, the newly named 4 Series convertible range kicks off from $88,800 for a diesel-engined 420d. That price, though, is more than $10,000 above the old entry-level pricing for the now superseded 3 Series convertible powered by a similar diesel drivetrain.
However, there will likely be a 420i petrol version in time starting at a lower price point.
Audi, meanwhile, leads its eight-variant A5-based convertible range with the turbo petrol-engined 1.8 TFSI priced from $67,190, while Mercedes-Benz’s C-Class is expected to add a new cabriolet version some time after it makes a generational leap later this year.
Lexus, meanwhile, offers its petrol V6-only IS250C convertible in three variants priced from $76,600, but wearing the old, dated pre-facelift skin.
Looking long, low and wide, helped in part by its longer wheelbase and wider tracks when compared with the 3 Series tin-top it replaces, the drop-top 4 Series closely mirrors its recently introduced two-door coupe sibling.
Inside, the four-seat cabin also adopts almost all of the styling and interior cues of the 4 Series coupe, including the driver-centric dash layout, although the big difference are front seatbelts that are integrated into the seats similar to the bigger 6 Series convertible range. BMW says the integrated unit was introduced because 3 Series owners complained that the seatbelt fixed to the B pillar moved around too much during high-speed, roof-down motoring.
Tucking the seatbelt away also makes it much easier to get into the tight, quite upright rear seats.
While we’re in the rear seats, it’s worth talking about an anomaly with the Australian-delivery 4 Series convertible stemming back to our newly introduced specifications for child seats.
BMW has had to install a zip with a somewhat uncomfortable metal pull into the seatbacks on either side of the 4 Series to allow access to a pair of top tethers added to the car to comply with the Australian version of the child restraint rules – something that is not needed in other markets the convertible sells in.
The brackets that the top tether clips into hang down into the space behind the wide, drop-down rear seatback that is also used to stow a wind deflector that fits behind the front seats. Because the tethers eat into this space, the wind deflector doesn’t fit, so instead of tucking it away and out of sight behind the seatback, Australian owners have to let it slosh around in the boot.
We were able to spend a short amount of time behind the wheel of each 4 Series convertible variant on a drive back to Melbourne from Daylesford in central Victoria.
The 420d is the price leader of the range. It is fitted with a 2.0-litre turbo diesel four-cylinder engine under the bonnet, producing only 135kW of power, but at 380Nm the second-highest serve of torque of the three-engine line-up.
It is also the most fuel-efficient, officially averaging 4.8 litres per 100 kilometres on the combined cycle.
From a standing start, the engine struggles a little with the convertible’s 1600kg-plus kerb weight, which makes it about as heavy as a Holden Commodore despite its smaller dimensions, as the peak torque rolls on at 1750rpm.
However, once rolling, the eight-speed gearbox fitted to the range by default slurs smoothly and intuitively, dropping only on steep uphill runs to keep momentum.
Over the course of the drive, the 420d posted a 6.0L/100km average despite some spirited driving and making next to no use of the engine’s idle-stop system.
And there’s the crunch BMW’s new 4 Series convertible is a car that you can point at a corner and enjoy. The drop-top has not lost any weight over its 3 Series-badged predecessor as it now has much more under-body stiffening, making it hug the road better than before.
Roof down, the rear headrests will shake a bit over rougher sections of road, but the lower-profile 18-inch alloys of the base model fitted with sticky Pirelli run-flat hoops combined with the firm but compliant suspension keeps the chassis well controlled.
The diesel variant uses a single-pot caliper up front compared with the petrol variants’ four-pot versions, but we didn’t get much of a chance to test the diesel’s reduced stopping power on our mainly freeway leg. We’ll leave that assessment for when we get a test car through the GoAuto garage.
By comparison, the $97,500 428i is more of a driver’s car. The turbocharged 2.0-litre engine produces less torque than the diesel – 350Nm – but it arrives much lower down in the rev range than for the diesel, at 1250rpm.
Combined with its 180kW of power, the petrol engine feels very sprightly compared with the diesel, providing much more driver enjoyment. It was fitted with good-looking 19-inch alloys – part of the Luxury Line pack fitted as one of three no-cost options available across the 4 Series convertible range – which once again rode quite well on our mainly freeway cruise.
Fuel use on test averaged 9.1L/100km compared with an official combined average of 6.7L/100km – good given that GoAuto was the last driver behind the wheel.
Happily, the range-topping 435i was the only 4 Series convertible we were able to punt through some tightly winding roads. It was also a good chance to try out BMW’s dynamics system that can cycle the car through four different settings ranging from fuel-miserly through to extra sporty.
The most apparent change is that BMW has done much to improve its electrically assisted steering system that in the previous generation of the 3 Series bordered on remote-feeling.
In the 435i and in its sport setting, the tiller feels nice and crisp, with only a slightly vague feeling on centre. Once again, and even when riding on 19-inch M-badged alloys as part of the standard M Sport package that also lowers the suspension, the ride and body control were both very well contained.
Braking, too, felt linear and progressive, although our test car was fitted with $1400 blue-coloured M Sport brakes as an option.
The 3.0-litre turbocharged in-line six-cylinder engine fitted under the bonnet of our test car, painted in striking Estoril Blue and fitted out with contrasting red leather trim, pulled like a freight train, delivering 225kW of power high in the rev range, but 400Nm of torque from just 1200rpm.
Around a twisty section of road the $126,900 range-topper performed admirably with just a little bit of shake but no shudder even in tight, rough corners even with the roof down.
As a consequence, the average fuel economy was ruined, posting 11.1L/100km despite its official average of 7.7L/100km, once again helped by an idle-stop system.
One of the big benefits of the new convertible range is that instead of having to stop to stow the roof in about 24 seconds, owners can now travel at speeds of up to 18km/h before an alarm starts beeping to tell them to slow down until it is under the bootlid, with the time now cut to 20 seconds.
Once in the boot, you can raise the stowed roof by 40mm to fit longer items in through the load-through space that wouldn’t ordinarily fit around the high boot lip. A protective plastic cover shows if the item will fit before you drop the folded roof down again.
The only nuisance with the boot is the need to depress release catches on either side of the rear seat bench to open up the big load-through space made possible by a single, large U-shaped rollover bar. Because the catches are at either extreme of the seatback, it’s a two-person job unless you like clambering into the rear seat.
BMW’s new 4 Series convertible has taken a significant step forward compared with the car it replaces, and feels all the better for it. The mid-range 428i appears to be the pick of the bunch, offering decent real-world fuel economy, a decent level of standard equipment, and the potential for plenty of driver satisfaction when pushed.
Despite our limited time behind the wheel, and until the arrival of the more manic M4 convertible that will make an appearance soon, it’s one instance where shopping in the middle of the range could produce the most reward.
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