The folding hardtop variant joins the fixed-roof Coupe in the new 4 Series family, which replaces the outgoing two-door 3 Series models.
Like the Coupe, the BMW 4 Series Convertible will launch with one diesel engine (420d) and two petrols (428i and 435i).
The BMW 420d’s 2.0-litre four-cylinder diesel engine produces an identical 135kW at 4000rpm and 380Nm at 1750-2750rpm as the outgoing 320d, yet fuel consumption falls 14 per cent to 4.8 litres per 100km and 0-100km/h acceleration improves two-tenths to 8.2 seconds when paired with the eight-speed sports automatic transmission.
The BMW 428i trades the 325i’s naturally aspirated inline-six for a turbocharged 2.0-litre four-cylinder petrol unit, and steps up 20kW/100Nm despite the 50 per cent cylinder count reduction. Producing 180kW at 5000-6500rpm and 350Nm at 1250-4800rpm, the model sprints to triple figures 2.0 seconds faster in 6.4sec while consuming 25 per cent less fuel at 6.6L/100km combined.
Like the 420d, the flagship BMW 435i retains the 335i’s turbocharged 3.0-litre inline-six petrol engine and peak outputs, which measure 225kW at 5800-6000rpm and 400Nm at 1200-5000rpm. Sprinting to 100km/h takes 5.5 seconds (down two-tenths) while combined cycle fuel consumption sharpens 15 per cent to 7.5L/100km.
At 4638mm long and riding on a 2810mm wheelbase, the new BMW 4 Series Convertible is 50mm longer between the wheels and 26mm longer overall. Vehicle weights range from 1680-1750kg, which BMW says translates to a reduction of up to 20kg for most variants, yet torsional rigidity increases by 40 per cent compared with the 3 Series.
The 4 Series Convertible’s three-piece roof now offers greater sound insulation, with wind noise reduced by up to 2dB. The folding panels can be stowed within 20 seconds at vehicle speeds up to 18km/h.
With the top down, the boot has a 220-litre capacity. This increases to 370 litres with the roof on – 20L more than its predecessor. A small ski port allows long items to be transported, while the entire rear seatback can also be folded forward to create a wide load-through space for bulkier items.
Five unique trim lines are available to personalise the exterior and cabin styling: standard, Sport, Modern, Luxury and M Sport – the latter featuring M Sport suspension and optional M Sport brakes with blue-painted calipers.
The BMW 4 Series Convertible will arrive in local showrooms in roughly nine months’ time, and is again expected to command a $10,000-$15,000 premium over the Coupe, approximately translating to prices of $85,000 for the 420d, $99,000 for the 428i and $120,000 for the 435i.