BMW 428i Luxury Convertible first drive

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.

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. 

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.