BMW's 4 Series Convertible has more individual appeal in second generation form. Jonathan Crouch takes a look.

Ten Second Review

BMW's second generation 4 Series Convertible switches to a fabric-folding roof and so can now offer a more credible alternative option to executive segment mid-sized cabriolet buyers not already swayed by the competing charms of rival open-topped versions of the Audi A5 and Mercedes C-Class. You won't get the large boot and cutting-edge driving dynamics of the 4 Series Coupe, but compensations come in the form of refinement, security and drop-top desirability. You'd like one.

Background

Sharper than its predecessor and echoing the bold style of its 4 Series Coupe showroom stablemate, BMW's second generation 4 Series Convertible aims to blend sporting driving pleasure and open-air thrills to continue the 35-year legacy in this model class that began with the Munich maker's first 3 Series Convertible.

Driving Experience

BMW has worked hard to ensure that this 4 Series Convertible's handling is as close to that of the equivalent Coupe as possible, using extra bracing and special panels to improve body rigidity, which the company says is 4% better than the previous generation metal-topped model. As usual with this model range, there's rear wheel drive and xDrive 4WD for the fastest models. Plus there's a freshly developed double-jointed spring-strut front suspension and a 5-link rear axle.

Engine-wise, the key news is introduction of 48V mild hybrid tech for the 2.0-litre 184hp diesel engine in the volume 420d. The same mild hybrid tech also features with the six cylinder diesels, the 430d (286hp) and the M440d (340hp). And it's on the quickest mainstream conventional petrol variant too, the six cylinder 374hp M440i xDrive, which features BMW's Sport differential, with electronically-controlled, fully-variable locking function in the rear differential. If you do want the ultimate fast version of this car, you'll be directed to the top M4 Competition M xDrive Convertible model, which has 510hp and gets to 62mph in just 3.7s.

Back in the real world, two conventional 2.0-litre petrol turbo 4 Series Convertible models also feature, the 420i (184hp) and the 430i (258hp). All the engines link up as standard with eight-speed Steptronic auto transmission, which can now be specified with a new optional Sprint function.

Design and Build

No doubt about the main talking point here. The rather inevitable switch from the previous model's metal hard top roof to the same kind of folding fabric top that rivals Audi and Mercedes offer. That means a 40% reduction in roof weight from a soft top that uses panel bow elements and a glass rear window for optimum acoustic and thermal comfort. The electric folding roof takes 18 seconds to open or close and can be used at speeds of up to 31mph. Otherwise, as with the Coupe version of this model, the key change is the adoption of a more vertical upright kidney grille, intended to reference classic BMWs like the pre-war 328 sports car.

Inside, the cabin follows some of the latest BMW design trends, with a revised dash layout including a smarter drive selector and a start button in the centre console. The 'BMW Live Cockpit Professional' dash set-up is standard, offering a fully digital screen layout that gives you a high-resolution 12.3-inch instrument cluster behind the steering wheel and a 10.25-inch iDrive infotainment Central Control Display. There are also re-designed sports seats and the option of a re-designed head-up display.

Market and Model

Sporty 'M Sport' trim is standardised this time round and prices start from around £46,000 for the entry-level 420i, which means a big price premium of almost £6,000 over the equivalent Coupe model. There's a further premium of around £2,200 if you want the 420d diesel version. You're looking at around £50,000 for a 430i. And think in terms of around £60,000 if you want the M440i xDrive model. The top M4 Competition Convertible M xDrive model is around £82,000.

Across the range as an option, there's an 'M Sport Pro' package which includes a special 'Sprint' function for additional bursts of speed and a sporty engine soundtrack in the cabin when the 'SPORT' driving mode is activated. Plus you get M sport brakes, 19-inch 'M light' alloy wheels, a rear spoiler in a high-gloss black, BMW individual high-gloss 'Shadowline' trim with extended features and BMW individual lights and M seat belts. You might also be interested in a browse through the M Performance Parts portfolio, from which you can order things like 20-inch M Performance forged light alloy wheels in a Y-spoke design with a Jet Black matt finish. Or maybe a carbon fibre finish for the front grille, front splitter and side skirts, as well as aero flicks for the front apron in high-gloss black.

Cost of Ownership

Mild hybrid technology has been included with all diesel engines and with the straight-six petrol unit of the flagship BMW M440i xDrive Convertible. Fitting a 48V starter-generator and second battery greatly increases the scope for utilising Brake Energy Regeneration and the electrical power it produces. The recuperated energy collected by the 48V battery can be supplied to the 12V electrical system or used for generating additional drive power when fed back to the 48V starter-generator.

All of which should promise a very competitive set of efficiency stats. Let's see. We'll start with the petrol models. The 420i manages up to 49.6mpg on the combined cycle and up to 131g/km of CO2. For the 430i version, the figures are up to 47.1mpg and up to 138g/km. For the M440i xDrive, the figures are up to 40.9mpg and up to 159g/km. What about the diesels? For the 420d, the official figures are up 67.3mpg and up to 111g/km. For the 430d, it's up to 50.4mpg and up to 147g/km. For the M440d xDrive, it's up to 44.8mpg and 165g/km. Finally for the M4 version, it's 27.7mpg and 231g/km.

Summary

In many ways, it's probably the most complete contender in this segment and, best of all, it looks as striking and expensive as a convertible of this kind should when the sun's out and all is right with the world. True, there are probably all kinds of ways of more sensibly spending the budget required for one of these. You know what though? Right here, right now, I can't really think of any....

FACTS AT A GLANCE

CAR: BMW 4 Series Convertible

PRICES: £45,800-£59,670 - on the road

CATEGORY: CONVERTIBLE – MID-SIZED EXECUTIVE

INSURANCE GROUPS: 33-46

CO2 EMISSIONS: 111-169g/km [WLTP]

PERFORMANCE: [430i] Max Speed 155mph / 0-62mph 6.2s

FUEL CONSUMPTION: [420d] (combined) 67.3mpg

BOOT CAPACITY: [litres] 300-385

WILL IT FIT IN YOUR GARAGE?: Length/Width/Height 4768/2081/1383 mm