BMW's first electric cabriolet has moved a step closer, with a new prototype providing the clearest indication yet that the German car maker is already well advanced on an i4 Convertible based on its Neue Klasse electric platform.

Set to make its public debut during the second half of 2027 before reaching UK dealerships in 2028, the new four-seat model is planned to form part of an all-new two-door i4 family.

Alongside it, BMW is also developing an i4 Coupé, which will effectively succeed today's Cluster Architecture (CLAR)-based i4 Gran Coupé, while the i4 Convertible expands the line-up with BMW's first dedicated open-top electric model.

The disguised prototype reveals several key details about the i4 Convertible.

Most obvious is the electrically operated fabric roof, which confirms that BMW has resisted calls to return to the folding metal hard tops used on earlier 3 Series Convertibles. Instead, it has retained a soft top similar in concept to that of today's G23-generation 4 Series Convertible. When lowered, the roof stows neatly beneath a dedicated rear tonneau cover.

The prototype captured here also provides the clearest look yet at how the Neue Klasse's dedicated electric platform has influenced the new open-top's design. It brings shorter overhangs at the front and rear, a longer wheelbase and proportions more closely aligned with the recently revealed i3 saloon.

Mechanically, the i4 Convertible is expected to borrow extensively from the new i3. The Neue Klasse platform supports an 800V electrical architecture, cylindrical battery cells and DC charging capability of up to 400kW.

Initial models are expected to mirror the i3 range, beginning with a rear-wheel-drive version before expanding to a four-wheel-drive i4 50 xDrive Convertible model featuring BMW's latest synchronous rear motor and asynchronous front motor. In i3 saloon specification, the dual-motor drivetrain develops 463bhp and 476lb ft. More powerful M Performance variants are also likely.

The i4 Convertible will not immediately replace its combustion-engined counterpart. BMW plans to continue producing the G23-generation 4 Series Convertible alongside the new electric model until around mid-2029.

Speaking to Autocar earlier this year, Joachim Post, who oversees the development of all new BMWs, said: "The 4 Series is an important car for us. It's more sporty, and BMW is a sporty brand which has a clear heritage also on the performance side. It will play an important role also for the future."