BMW lists dynamics as one of its three priorities for the 4 Series Convertible, along with efficiency and functionality. To that end this model has bespoke suspension tuning and a lower centre of gravity compared to the current 3 Series saloon, along with the signature 50:50 weight distribution.
There are a couple of points that will check our early enthusiasm, though. 40 per cent increase in rigidity or not it remains true that slicing a third out of a contained structure will diminish its integrity, and past experience of our own 435i coupe long termer has proven that even the fixed-head version falls some way short of being an electrifying drive.
The 4 Series Convertible will be available with three engines at launch; a four-cylinder diesel, a four-cylinder petrol and a six-cylinder petrol, all turbocharged. It's the range-topping 435i that we drive here, complete with eight-speed automatic gearbox.
What stands out first is the quality of the cabin, shortly followed by the drivetrain, which is perfectly suited to a car of this nature. The gearbox shifts quickly and cleanly while the engine pulls effortlessly from all points in the rev range. There's just enough six-pot snarl under hard acceleration, too, without it being unrefined or intrusive.
With the roof in place there's no real evidence that it folds away, so well contained is wind noise. What's less impressive, though, is the ride quality, which on anything other than the very smoothest surfaces is never better than fidgety. The steering, meanwhile, is accurate enough, but never communicates anything of value back to the driver.
As long as the road surface allows, the Sport mode is best selected when the driver does want to start hustling. This adds weight to the steering, which does little to improve it, and firms the suspension up a touch. As the road begins to twist and turn and the driver commits harder to corners, there is a slight but definite sense that some rigidity has been lost compared to the coupe. There isn't any scuttle shake and nor is there any unwelcome vibration in the steering column, but it's clear that the suspension tuning has been compromised and there is, as a result, a degree of imprecision at turn-in and a lack of agility in rapid direction changes. A notch or two back from maximum attack, though, the 4 Series Convertible does carry plenty of speed along a challenging road with enough composure to encourage the driver to continue at such a pace.
BMW 435i Convertible
Engine: 2,979cc 6-cyl, turbocharged
Transmission: 8-speed automatic, rear-wheel drive
Power (hp): 306hp@5800rpm
Torque (lb ft): 295lb ft@1,200-5,000rpm
Top speed: 155mph (limited)
MPG: 37.7mpg (claimed)