From £29,7006
Fitted with the mid-range engine, Munich's 4-series cabrio lacks top-down stateliness, which is hard to forgive in a car built for stylish cruising

What is it?

It’s the BMW 4-series family’s drop-top in 428i auto spec, meaning it’s powered by a 242bhp turbocharged 2.0-litre four-pot sending power to the rear wheels via an eight-speed automatic transmission.

This is the 4-series convertible’s mid-range engine, bookended by the 420d’s 181bhp 2.0-litre turbodiesel and the 435i’s 302bhp turbocharged straight six, both of which we’ve already sampled.

The 4-series convertible picks up the baton from the E93 3-series drop-top, gaining 26mm in length and 50mm in wheelbase, while added track width and a 10mm drop in ride height also help it assume a more planted and athletic stance.

The 4-series coupé’s svelte lines aren’t quite recreated in the convertible, though: the three-piece folding hard-top dictating a more angular trailing roofline than that of its fixed-head brother.

Torsional rigidity is 40 per cent higher than in the E93 (which also used a folding hard top), although the new model is claimed to be up to 20kg lighter. That said, our car’s 1775kg kerb weight is a staggering 230kg more than its coupé counterpart’s, and 115kg more than that of the equivalent Audi A5 cabriolet, which uses a lighter fabric roof. 

Even with the roof up, a considerable 53.4 per cent of the 428i’s mass lies over the rear axle (it’s 54 per cent in the manual version), but BMW has reconfigured and strengthened the rear suspension in a bid to counteract the dynamic implications of this sumo-on-a-see-saw weight distribution.

Entry-level SE spec is generous, with highlights including parking sensors fore and aft, leather upholstery, heated front seats (electrified as standard in the convertible to aid rear-seat access), colour 6.5in screen and Drive Performance Control (DPC) to toggle dynamic settings. 

Our car’s Luxury spec adds £2500 to the SE’s £38,570 price tag and brings the likes of 18in alloys, sports seats, sat-nav and smatterings of chrome and wood.

What's it like?

The cabin is mainly carried over from the 3-series, so is smart and effective rather than beautiful, but the driver’s seating position and ergonomics are sound.

In the two rear seats, legroom is still tight despite the wheelbase gain, the seatbacks are conspicuously upright and headroom is cosy for taller occupants with the roof up – not especially hospitable for adults, then.

The boot swallows just 220 awkwardly distributed litres when the roof is stowed and you gain just 150 litres when it isn’t, but that’s only 10 less than in the Audi A5 cabrio.

The roof itself takes 20 seconds to fold up or down, and can be moved at up to 8mph; the A5’s is a couple of seconds quicker and operates when travelling at up to 30mph. The car wobbles a bit as the complex mechanism whirrs away, too.

With the roof up, the cabin feels impressively cocooned, and although you can’t hear much from the engine as it smoothly gathers momentum from 2500rpm, you can feel it fighting the convertible’s extra mass. 

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Drop the roof and things change – in town, there’s a bassy drone from the exhaust, mixed in with whooshes from the turbo and upshift ‘whumps’ under throttle, none of which is especially dignified or relaxing in an open-top tourer.

Motorway refinement is good, though: with the £265 wind deflector in place, you can chat away comfortably at 70mph. The eight-speed auto ’box is as slick as ever, blurring upshifts with DPC in Comfort mode and flashing through them in Sport.

Putting our car’s slightly neurotic Variable Sport Steering (an unnecessary £250 option) to one side, the 428i can’t mask its uneven weight distribution, or its lack of top-down rigidity.

Roll is relatively well contained, but the car isn’t comfortable taking corners at pace, feeling significantly less tied-down than its fixed-head brother, and rippled Cotswolds roads elicited pronounced pattering from the suspension, much of which resonated through the steering column.

Should I buy one?

You can understand the 428i convertible’s shortage of dynamic edge, but its lack of top-down stateliness – both in terms of powertrain refinement and ride quality on our weathered roads – is less easy to swallow. 

In terms of the engine, an entry-level 420i option, using the calmer 181bhp version of the same unit, might have been more in line with the car’s relaxed remit.

As it is, the 420d is slightly cheaper and more economical, but also suffers refinement ills, which leaves the pricey but smooth-running and rapid 435i as the 4-series convertible’s engine of choice.

Depending on trim choice, the A5 cabrio in front-drive 222bhp 2.0 TFSI Multitronic form – which is slightly slower but lighter and cleaner than the 428i auto – costs at least £1600 less. Despite the BMW’s added modernity and sophistication over the Audi, it’s hard to argue that its premium is worthwhile.

BMW 428i Luxury Convertible

Price £41,070; 0-62mph 6.4sec; Top speed 147mph; Economy 42.8mpg; CO2 154g/km; Kerb weight 1775kg; Engine 4 cyls, 1997cc, turbo, petrol; Power 242bhp at 5000-6500rpm; Torque 258lb ft at 1250-4800rpm; Gearbox 8-spd automatic

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gazza5 1 August 2014

M135i or M235i?

I have to say the only bmw I would personally consider is a M135i - its not the prettiest car in the world - but for me is ideal and not far off a golf when you add the perfomance pack. I need 5 doors so can't have a M235i.

I do agree with other posters - to me a BMW is suppose to be a drivers car, with the lower cars becoming fwd drive car enthusiasts will go elsewhere. I know a lot of people don't really care about the car they have - but some of us still do. I may only drive a astra diesel at present but my financial situation is now changing and I would like to experiance a straight 6 engine before they do completely die of extinction.

I would also like a v8 but will have to wait till I visit america to experiance one.

spqr 30 June 2014

2 Many or 2 Few?

Fitting BMW's new 1.5 3 cylinder petrol turbo engine to the 3/4 Series might be a good idea. It is certainly capable of producing as much power as the N20 petrol engine currently used in the 3/4 Series as evidenced by its use in the i8. From all accounts it is a zesty and charismatic engine just like BMW engines used to be. It may even be better on fuel consumption. As stated in my long post above having driven 2 variants of the N20 neither is as economical as BMW claims and in fact no more economical than the 3 litre straight six in the E92. The only reason BMW have switched to this travesty of an engine is cost (it is much cheaper to engineer resulting in more profit for BMW) and EU emissions (which wrongly place CO2 as the be all and end all). On another note, as voyager12 says BMW's current design language is terrible. I own an E92 330i Coupe which remains almost crease and clutter free in design and is elegant and restrained. The new 3/4 Series cars have at least 7 different "character lines" or creases at the front end. This is particularly noticeable at the junction of the A pillar and the bonnet. Far too fussy and inelegant. When I pointed this out to the salesman he said it was all because of crash regulations and pedestrian impact rules. If one looks at the new Ford Mustang it is clear designers can make a car striking and iconic without silly folds and creases everywhere. The F-Type Jaguar also shows how to design an elegant modern car that complies with all the necessary legislation. BMW has definitely lost it's mojo.
JOHN T SHEA 29 June 2014

TOO FEW CYLINDERS, OR TOO MANY?

TOO FEW CYLINDERS, OR TOO MANY?
Six cylinders good, four cylinders bad? Try three! I've heard no complaints about harshness in the Mini and I8 threes.

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