Despite slowing sales in the face of SUVs’ growing popularity, the station wagon continues to feature in many a model line-up, and so it appears to be the case for the forthcoming BMW 3 Series. Following the sightings of G20-generation test mules, a development vehicle for the corresponding estate version has now surfaced, slated to bear the model code G21.

At first glance, the G21 development car here appears to be wearing M Sport kit, with a front bumper sporting a deep, wide air intake bookended by a smaller one at each corner. The front of the car corresponds with what we’ve seen on G20 test mules so far, and the mid-body character line goes from the front fender to the top of the rear wheel arch.

Given the G21’s wagon shell, the long roof ends in a sloping rear windscreen, and when viewed in profile, the tailgate wears a full-width bulge which accentuates the tail lights, and is in line with the secondary character line which goes from just ahead of the A-pillar and above the door handles.

The test vehicle photographed here also sports blue brake calipers and considerably-sized brake discs, which may suggest the inclusion of an M Performance model for the G21 3 Series line-up; going by the G01 X3 M40i and the G02 X4 M40d, this could mean the use of the 360 hp/500 Nm 3.0 litre turbo six petrol, the 326 hp/680 Nm turbo six diesel, or both.

This junior wagon can be expected to feature the full engine line-up in both petrol and diesel forms, in rear-wheel drive and all-wheel xDrive guises. With the G20 3 Series sedan slated for its debut later this year, the G21 station wagon can be expected to follow suit a few months after that, possibly in 2019.

GALLERY: G20 BMW 3 Series Sedan spyshots