This X4 prototype seems to be fitted with a more aggressive front fascia that includes a separate bank of LED driving lights.
Along the sides, the new X4 has a more curvaceous roof line leading into a liftback-style rear, and unique door pressings with bulkier detailing near the sills.
Under the skin, the X3 and X4 will employ BMW's CLAR architecture, which has already been used to underpin the latest 5 Series and 7 Series models. As with all modern architectures, it makes heavy use of high-strength steel, aluminium and other lightweight materials.
Motivation for both crossovers will come from turbocharged four- and six-cylinder petrol and diesel engines, with a three-cylinder models also highly likely.
As with the current generation models, the new X3 and X4 should share the same dashboard and interior design, with differences limited to trim and specification levels. Spy photos from April 2016 revealed the new X3's dashboard will feature a free-standing tablet-style screen for the iDrive infotainment system.
The X3 is expected to debut later this year, with the X4 likely to follow on its heels a few months later. Both models probably won't go on sale in Australia until some time in 2018.