Compared to earlier prototype vehicles, this latest prototype features a small boot lip spoiler, sits slightly lower to the ground, and rides on a larger alloy wheels and lower profile tyres.
It also gives us a clear look at the design of the new 3 Series' sports side sills and rear bumper, which includes a trapezoidal surround for the exhaust tips.
It's hard to make out other design details as BMW has stapled false body panels to the fenders, doors, and front fascia.
Thanks to lightweight materials, including aluminium, high-strength steel and, potentially, carbon-fibre, the new 3 Series could shed up to 100 kilograms in weight.
Under the bonnet, the 3 Series will be powered by a selection of turbocharged three-, four- and six-cylinder petrol and diesel engines.
Given that the current car dates back to 2011 and BMW likes to stick to seven year model cycles for its mainstream products, the next-generation 3 Series is expected to go on sale globally in 2018.